Tips, challenging expert’s qualifications, impeaching expert, probing foundation

by Edward L. Birnbaum, Carl T. Grasso
& Justice Ariel E. Belen*

Excerpted from New York Trial Notebook

A.  Tips For Cross-Examining Experts

§27:50    Whether and How to Cross

The basic consideration in deciding whether and how to cross-examine an expert is: will it be helpful or detrimental to the case? If the expert is “litigation savvy,” this decision requires a risk-benefit analysis. Consider the following:

  • How was the expert received by the jurors? Did they like him or her? Appear to accept what the expert said? If the jurors liked the expert, is it probable the cross-examination will change this feeling? Or, will it turn them off to your position?

  • How important was the expert’s testimony? If the testimony was only on minor issues, is the time and effort to do the cross-examination and the potential risk of turning off the jurors worth the probable benefits?

  • Do you seriously dispute the expert’s opinions? The plaintiff may need to put on expert testimony to make a prima facie case, but if, for example, culpability is essentially conceded, there may be little point in cross-examining plaintiff’s liability expert. Similarly, where there is no dispute that a plaintiff is seriously injured, there may be nothing gained in cross-examining plaintiff’s medical experts.

  • How experienced is the expert? What is his or her style of answering questions? How has the court been handling the proceedings? If counsel cannot keep control of the examination [see §27:57], the expert may simply seize the opportunity to reinforce the opinions expressed on direct.

  • What do you have to cross-examine the expert with? What points do you plan to make? If there are no strong points to be made with the expert, the jury will not appreciate what may seem like an aimless waste of time.

  • If you intend to cross-examine the expert, how long do you want to keep him or her on the stand? It is usually best to score your points with the expert as quickly as you can and get him or her off the stand; but some experts require more lengthy treatment. Experts who are smooth and glib may need to be worked on to remove the gloss. When they are pressed and become tired, they may turn testy or condescending; that is when they are most vulnerable.

Advice for cross-examination of lay witnesses [see Ch 25] may or may not be helpful in the cross-examination of experts. Many expert witnesses are old hands at testifying in trial, and have seen the inside of a courtroom more often than counsel on either side of the case. While some of the techniques suggested for cross-examining lay witnesses may be effective in individual cases (e.g., stepping up the pace of the examination, wording the same questions differently, etc.), in many instances, the expert is too savvy for such tactics, and may even turn them to counsel’s disadvantage. While a successful cross-examination of the other side’s expert may go a long way toward helping your case, an unsuccessful cross-examination may sink it irretrievably.

§27:51    Request Break After Direct

Depending on the dynamics and timing of the trial and how you believe the court will react, consider requesting a break after the expert completes direct, to give you time to organize your thoughts and write down key words for questions you will want to ask. If direct winds up a few minutes before the normal lunch break or the end of the day, consider asking the court to recess “just a little bit early”; the jurors will probably appreciate this. Of course, take every opportunity during breaks while direct is still going on to make notes and draft potential questions. If the court is not inclined to recess early, consider asking relatively innocuous questions to use up time until the court permits a break, or ask to see the expert’s case file (and go through it “thoroughly,” i.e., ask questions about what is in the expert’s file to use up time).

§27:52    Maintain Civil, but Not Bland Demeanor

While counsel should always remain scrupulously civil and polite when cross-examining an expert, there is no reason why the examination must be conducted in a bland monotone. Many counsel begin expert cross-examination in a low key manner, and build in intensity to make a point. However, if the moment seems right, do not hesitate to jump right in, particularly if you begin on the last point the expert made in conclusion on direct. For example, where an un-seat-belted plaintiff had been ejected from a car that rolled over, and the last point the expert made on direct was that most people did not wear seat belts, the cross-examiner might consider forcefully asking as the lead off question, “Does that make it right?” to secure the admission that people should wear their seat belts.

If the expert says something that is way off base, consider allowing at least a bit of disbelief to show. An expert who insists he or she can estimate the speed of a vehicle during a collision without making any measurements, calculations, comparisons or other analysis might merit some skepticism in your tone of voice. The expert who claims to be able to detect dimensional differences of thousandths of an inch by eye alone is probably worth at least a raised eyebrow. The expert who opines that molecules of hydrogen gas collected under the rear seat of a car over a period of a week, were released when the seat was removed, rose until they bounced off the inside of the roof and went back down to the level of the seat probably rates an askance, “Did I hear you right…?” [These are all instances the authors have personally encountered!]

§27:53    Three Tenets of Cross-Examination

The standard in cross-examining experts is similar to that of any other witness:

  • Use leading questions calling only for yes or no answers;

  • Do not ask questions that you do not know how the witness ought to answer; and

  • Know when to stop. [See Ch 25.]

While it is not always possible to adhere to these tenets, counsel must always be aware of the potential consequences of violating them. For example, it may be appropriate to ask a non-”yes” or “no” question that calls for discrete factual information—”when,” “where,” “how many”—but a “what,” “how,” or especially a “why” question gives the expert license to say practically anything he or she wants.

§27:54    Keep Questions Short

Keep the questions to the expert as short and simple as possible. Long, complicated questions lend themselves to “explanations.” Rather than load the question with details, break it into two or more questions. However, do not assume that just because a question can be answered “yes” or “no,” that the expert will answer “yes” or “no.” Savvy adverse experts look for opportunities to add their own self-serving commentary to even the simplest questions.

§27:55    Avoid Multi-Part Hypotheticals

Avoid asking an adverse expert multi-part hypothetical questions. If given the chance, most savvy experts will happily explain why elements A, C and G of your hypothetical are simply not true, or smugly expound on why A, B, C, D, E, F, G and H do not add up to X in any event. If you feel you must pose a hypothetical question to the adverse expert, feed the expert one element at a time in short, simple questions. For example, “Mr. Expert, A is true, isn’t it?” If he will not agree that A is true, ask him to assume it is true for the purposes of the question, and tell him that the jury will ultimately decide if A is proven to be true or not. Only after A is accounted for should you ask about B. After all elements are accounted for and you have asked, “then X must follow, right?” do not expect a simple “yes” or “no”; rather, brace yourself for a “yes, but …” with an explanation, or a “no” with a discourse on why X does not follow. Only pursue such a line of questioning if you are prepared to live with the inevitable explanations.

§27:56    Avoid a Dialogue

As much as you should develop the sense of a dialogue with your expert on direct, avoid this when questioning an adverse expert. If you fall into a conversational mode with the other side’s expert, his or her “explanations” will seem natural. If you keep the questions succinct, calling for very discrete bits of factual information, the expert will sound unnatural in giving long explanations, and the jurors may become tired or even suspicious.

§27:57    Maintain Control of Expert

Critical to all cross-examinations is for the questioning counsel to keep control of the witness and structure the questioning to limit the responses. Experts are the most dangerous witnesses to cross-examine. Whether or not an expert is an old hand in the courtroom, the expert will probably be of the opinion that he or she knows far more about the subject than counsel (and the expert may be right). Some experts resent cross-examination, feeling that counsel is impugning their honesty and integrity. (Of course, that may be exactly what counsel is trying to do!). Such experts will take every opportunity to turn counsel’s cross-examination to their own side’s advantage, even to the point of attempting to make the questioner look foolish. If given an opening, the expert will “explain” an answer by reiterating or even amplifying his or her direct testimony. If an expert has been properly prepared, “traps” may have been laid for the unwary cross-examiner.

If, despite all counsel’s efforts, the opposing expert says something palpably improper on cross-examination, be sure to timely object and move to strike the comments, or for a mistrial. Failure to do so will waive the issue on appeal. [See, e.g., Picciallo v. Norchi, 147 AD2d 540, 537 NYS2d 837 (2d Dept 1989) (defendant’s expert allegedly made improper and prejudicial comments during cross-examination, but plaintiffs’ failure to object or move for a mistrial precluded a claim that they were denied a fair trial).]

§27:58    Cut Off Lengthy Explanations

If the expert begins a lengthy explanation to what was in fact a simple question, interrupt the expert with a polite but firm, “excuse me doctor, but I believe the question called only for a yes or no answer,” or, “Ms. Expert, my question simply called for a yes or a no. If your counsel wants you to give an explanation, I am sure he will ask for it on redirect.”

Some savvy experts will respond to a yes-no question with a “mini” explanation, giving no real opportunity to interrupt. Rather than fence with the expert, continue questioning in a polite way. If the expert continues with this technique, consider prefacing your question by saying, “Please tell the jury, yes or no, …” or, “Let me ask you this question, doctor, which you should be able to answer simply yes or no … .”

§27:59    Control the Lengthy Response

Some experts, after responding at length to a cross-examination question, will pause, and then indignantly interrupt your next question with “Excuse me, counsel, I haven’t finished my answer.” If the expert does this repeatedly, consider saying something like, “Ms. Expert, I don’t mean to keep interrupting you, but I seem to be having trouble knowing when you’ve finished. How about doing us all a favor, and when you’re finished with your answer, raise your hand to let us know you’re done.”

If the expert’s response has gone far beyond your question, and you think the court’s reaction will be favorable, interrupt the expert and ask him or her to simply answer the question. If the expert’s answers are palpably inappropriate, consider requesting the court to instruct the witness to respond to the question and move to strike the non-responsive part of the answer. Be careful: if such requests are denied, the jurors may think the court is giving its blessing to the expert’s long-winded explanations. A comment by the court to the effect, “no, counsel, I think Ms. X should be allowed to explain her answer” may cause the jurors to think you are trying to keep them from hearing something they should hear. This could hurt your credibility. Keeping your questions pointed and short will increase the chances of the court siding with you and instructing the witness to simply answer the question.

§27:60    Do Not Give Expert Opportunity to Fix Gaffes

If you have obtained answers you wanted, or the expert said something foolish, move on to something else. Do not give the expert an opportunity to go back and clean up his or her answers. For example, an expert had challenged the validity of a 1979 automotive patent by saying that back in 1962 the principle of the patent would have been obvious to automotive engineers. On cross-examination, he was asked how many automotive engineers he was acquainted with in 1962 (the expert was an academic who had never worked in industry). When he responded, “I don’t know how to answer a question like that,” interrogating counsel smiled and briskly said, “All right, if you can’t answer that, I’ll ask you something else,” and quickly changed the subject.

§27:61    Remain Flexible

While prepared questions and areas are valuable, always remain flexible to follow up on areas that present themselves based on the expert’s answers to your earlier questions. Do not hesitate to improvise questions “on the fly,” depending on what answers the expert gives; and likewise, do not be reluctant to jettison questions you may have spent hours preparing, but that, based on developments in the courtroom, have lost their usefulness.

§27:62    Avoid Dead Spots

It is very important to maintain a constant flow during cross-examination, and to avoid dead spots. If you have scored a significant point, you may want to quickly move to a new area. An outline with key words highlighted may help you get quickly back on track and avoid embarrassing, long silences.

§27:63    Ask Court to Direct Witness to Return

If you have not completed your cross-examination of the expert by the end of the day’s session, be sure to ask the Court to direct the witness to return the following day. In Young v. Forest Hills General Hospital, 32 AD2d 652, 652, 301 NYS2d 443, 443 (2d Dept 1969), the reviewing court found that “there was a full and complete cross-examination of plaintiff’s expert witness” and the expert’s “failure to return for the completion of his redirect examination and for re-cross-examination was impliedly acquiesced in by defense counsel in their failure to seek a direction for his return the following day in the face of the probability that he would not otherwise reappear.” A somewhat different situation arose in Notrica v. North Hills Holding Corp., LLC, 43 AD3d 1119, 842 NYS2d 577 (2d Dept 2007). In the midst of a non-jury trial, the court adjourned the trial during cross-examination of plaintiff’s expert to allow defendant’s counsel to take care of a personal matter, the expert returned on the adjourned date but left the courthouse when a dispute over his fee arose. The Second Department held that the trial court should have granted plaintiff’s application for a continuance to either get the expert back or obtain a new expert, and reversed the trial court’s dismissal of the complaint.

§27:64    Know When to Stop

Perhaps more so than cross-examining lay witnesses, knowing when to stop cross-examining an expert is crucial. If you score a significant point, quickly decide if it is more worthwhile to sit down, or to go on to make a few additional, perhaps minor points. Always remember that jurors form judgments based on impressions. The best thing you can do for your case is to finish with the other side’s expert while the jurors are thinking “what a fool/liar he is!”

§27:65    Break Rules for Right Opportunity

As in all things, exceptions to normally hard and fast rules can crop up, and you should not hesitate to “break the rules” if an opportunity presents itself. If an expert is back on his heels, flustered and hesitant, he may be in no frame of mind to be able to respond with a lengthy explanation, or even to concoct a reasonable response. One automotive “safety” expert had criticized a lack of a “shield” on a part attached to the undercarriage of defendant manufacturer’s automobile, saying this made the car unreasonably dangerous. Cross-examination brought out that the expert’s own car, a far newer model made by a different manufacturer, also lacked such a “shield,” and the expert admitted that he had not affixed such a “shield” himself. The cross-examiner took a small chance and asked, “why not?” The expert’s off-the-cuff reply, that the car was a leased vehicle, sounded lame and the jurors were rolling their eyes even before he finished his answer.

[§§27:66–27:69 Reserved]

B.  Challenging Expert’s Qualifications

§27:70    Whether to Challenge

Since “[t]he extent of the expert’s qualifications is always a proper subject for the jury on the question of the weight to be given to his testimony” [Meiselman v. Crown Heights Hospital, 285 NY 389, 398, 34 NE2d 368, 371 (1941)], cross-examination on the expert’s qualifications is always proper. However, counsel should consider carefully to what extent, if at all, an opposing expert’s qualifications should be challenged. Counsel may not want to contest the expert’s qualifications if:

  • Counsel intends to introduce favorable material through the expert.

  • Counsel does not dispute the expert’s opinions.

  • The expert is indisputably highly qualified (or, at least more so than counsel’s own expert).

§27:71    Objectives in Challenging Qualifications

Counsel’s objectives in challenging an expert’s qualifications may be twofold, and not mutually exclusive:

  • Adversely affect the weight the jury will accord the expert’s opinions.

  • Persuade the court to preclude the expert from giving opinions, or to strike opinions already given.

While the second objective is highly desirable, the tendency of most judges is to allow someone with a semblance of credentials to qualify as an expert, with the weight to be accorded their opinions left to the jury. [See Ch 15.] If an expert’s testimony is precluded, that side may be left with an irreparable hole in their case, entitling the opposing side to a directed verdict. [See Ch 35.]

In the grand scheme of things, sometimes degrading the other side’s expert in front of the jury is actually a better outcome than having the expert outright precluded. If enough doubt is cast on the expert’s fitness to testify, the other side’s entire case may be infected; plus, you may still have the issue on appeal, rather than the other side.

§27:72    Expert Must Be Qualified in Area of Questioning

Very often, experts may be highly qualified in one or more fields, but lack competence in a specific area. As the use of experts in litigation has grown, more and more individuals with differing backgrounds have entered this financially lucrative fray and hold themselves out as experts in a bewildering variety of fields. Sometimes persons with only a general technical background portray themselves as experts in highly specialized fields, or attempt to extend their expertise into areas in which they have no competence.


  • A Ph.D in mechanical engineering may be expert in the theoretical design of mechanical systems, and may be competent to tell the jury how an automobile seat belt retractor is theoretically supposed to work, but may have no expertise in studying a seat belt that has been through a collision to opine whether or not it worked properly in the accident.

  • A civil engineer may be an expert in building bridges or dams, but have no experience in designing highways, and may lack qualifications to tell the jury why a given roadway was or was not designed in a safe manner.

  • A vocational rehabilitation expert may have spent years working with injured people, and may know a lot about how disabled people are or are not able to cope with their injuries, but may lack the medical background to give opinions on how those people got their injuries.

If counsel cannot persuade the court to exclude these people from testifying altogether, the objective should be to restrict the opinions they are allowed to give or to obtain limiting instructions from the court.

§27:73    Treating Physicians and Causation

Sometimes an expert who is in the case to address one area will happily testify in a related area beyond his or her true expertise. A treating physician testifying about an injured plaintiff’s medical condition, treatment, and prognosis is sometimes led into testifying about how the plaintiff received the injuries. Attention to this issue is particularly important as courts tend to read causation issues broadly. [See, e.g., Moreno v. Roberts, 161 AD2d 1099, 557 NYS2d 657 (3d Dept 1990) (no error to permit defendant’s examining physician to testify as to lack of causal relationship between accident and plaintiff’s injuries, since “causation was placed ‘in issue’” in his report which stated a diagnosis that a condition was congenital) and causation issues may be far more subtle than a simple accident equals injury pronouncement by a treating physician. Issues of injury causation may range from self evident (a finger cut off by a punch press) to quite subtle (a head injury suffered by a person ejected from an automobile—did she get the injury inside or outside the car?). Counsel should be vigilant in challenging experts who stray into areas where they are not truly expert. [See Garcia v. City of New York, 104 AD2d 438, 478 NYS2d 957 (2d Dept 1984) (plaintiff was shot in the leg and issue was whether the shooting was negligent or intentional; testimony of plaintiff’s medical expert, received over objection, was entitled to no weight, as he was not a ballistics expert, and much of his testimony was beyond his expertise; verdict for plaintiff reversed and complaint dismissed).]

§27:74    Safety Experts

One type of expert whose competence is often susceptible to challenge is the self-styled “safety expert.” This individual may never have worked in industry or academia, and yet may claim to be expert in the “safety” of everything from automobiles to coffee pots, garbage trucks to manure spreaders, step ladders to zippers. Often this type of expert’s main claim to being qualified is that he has in the past been permitted to testify as an expert about the area in some other court. Such an expert’s qualifications should always be heavily challenged, with the objectives of having the expert disallowed or laying the foundation for appealing an adverse verdict for the trial court’s failure to prohibit or limit the testimony, as well as discrediting him in the eyes of the jury.

§27:75    Methods of Challenging Qualifications

If counsel decides to challenge the expert’s qualifications, it may be done in several ways, depending on how the expert is presented.

Alternative 1: An expert’s testimony on direct normally begins with his or her qualifications. [See Ch 26.] Proponent counsel may then offer the witness as an expert in the field of “X.” If this happens, counsel may:

  • Stipulate or otherwise acquiesce to the expert’s qualifications.

  • Request to voir dire the expert on the issue of qualification.

  • Advise the court you wish to reserve your questions about the expert’s qualifications until cross-examination.

Alternative 2: Proponent counsel may simply launch into the expert’s main testimony. If this happens, counsel may:

  • Object on the ground that the expert’s qualifications have not been established.

  • Interrupt and request leave to question the expert on voir dire.

  • Stay seated and silent, in effect reserving the right to cross-examine on qualifications as part of the main cross-examination.

§27:76    To Voir Dire or Not to Voir Dire

The decision of whether to request voir dire must depend on the circumstances of the case: how the expert’s background came across; whether you have solid adverse material to challenge the expert with; and how you believe the court and jury will react. Many judges will allow an expert’s qualifications to be tested on voir dire; others will tell you to “save it for cross-examination.”

Examining an expert on voir dire may have the following advantages:

  • Persuade the court to disallow or limit the extent of the expert’s testimony before the expert has given any opinions;

  • Plant a seed of doubt with the jurors before they hear any opinions;

  • Break the flow of the expert’s presentation.

On the other hand, voir dire may have the following disadvantages:

  • If you are unsuccessful in persuading the court to disallow or limit the expert’s testimony, the jury may feel the court has given its imprimatur to the expert’s testimony.

  • Unless adroitly done, voir dire may simply give the expert an opportunity to repeat or expand upon his or her qualifications.

  • If you are unable to score any significant points, the jurors may think you have simply wasted their time.

After completing voir dire, counsel may object to the expert’s being qualified, may request that the court limit the areas in which the expert may testify, or may simply sit down.


If you think you have cast enough doubt on the expert’s qualifications to earn at least a limitation, ask to approach the bench and make your argument out of the hearing of the jury. If the court grants an exclusion or limitation, the jury will be made aware. If the court is not persuaded, the jury will be spared hearing the court deny your objection. The tendency of many trial courts is to allow testimony from marginally qualified experts, expecting that the jurors will be able to allocate the appropriate weight to the testimony. If the jurors hear your motion to exclude or limit the expert denied, they may conclude the court has placed its stamp of approval on the expert’s testimony.

§27:77     Techniques for Challenging Qualifications

If your expert has superior qualifications, consider certain limited examination to highlight the contrast in qualifications. If the adverse expert is a university professor who testified that he is training the engineers of tomorrow, bring out that he himself has never worked in industry as an engineer.

If the expert claims to have practical experience but lacks educational credentials, bring this out, along with the fact that formal education in the field is indeed available; you will either be planning to bring out your expert’s formal education in the field, or have already done so.

Bring out that the expert has never published anything relevant to his area of testimony, particularly if your expert has.

If the expert is not a member of the leading technical society in the field, bring this out; if he or she is, but has never held office in the organization and your expert has, bring this out.

Let the jury know that the expert lacks experience in the field: that the “safety expert” has never worked on the design of a truck’s brake system; that the doctor has not performed the medical procedure in question within the last 20 years; that the business appraiser has never worked in the type of business he is appraising; that the expert economist’s career has been exclusively in academia and that he has never worked for any company that permitted him to put his economic theories into practice.

A jury, hearing no dispute over an expert’s competence, will tend to accept the opinions stated if they make sense. If counsel intends to challenge an expert’s opinions but does not contest his expertise, he or she had better be prepared to mount a vigorous attack in some other fashion. If there is no challenge to the witness’s qualifications, the jury will need substantial contradictory evidence to feel justified in rejecting the expert’s opinions.


If you decide it is not worthwhile challenging the witness’s expertise, offer to stipulate that the witness is adequately qualified to testify as an expert. [See Ch 15.]

[§§27:78–27:89 Reserved]

C.  Impeaching Expert

§27:90    Meaning of Impeachment

When we speak of impeaching an expert, we are not talking about attacking the substance of the expert’s opinion. Rather, we are talking about attacking the expert as a person, suggesting to the jury that the witness’s opinions are not worthy of belief, no matter how plausible they may seem, because the person expressing the opinion is not worthy of belief.

Experts are expected to express opinions beyond the knowledge of lay persons. Even where the expert explains the basis of the opinion at great length, the jurors are still at some level expected to accept the opinion on faith. If the jurors’ confidence that the expert is giving a straight story can be shaken, the expert’s entire testimony may be tainted. If it can be demonstrated that the expert has stated a falsehood, the conventional wisdom is that the expert is thereafter destroyed, that the jurors will reject any opinion he or she may have given on direct.

While outright untruths by experts are rare (or at least, usually difficult to establish), there are many other ways experts may be impeached. The only limitation should be counsel’s imagination. Even a typographical error on an expert’s C.V. (in one case, the incorrect number of a patent) tends to diminish the expert in the jurors’ eyes.

§27:91     Limits to Proper Impeachment

There are, of course, limits to proper impeachment of experts. For example, counsel cannot pit his or her own credibility against that of the expert. In Senn v. Scudieri, 165 AD2d 346, 567 NYS2d 665 (1st Dept 1991), plaintiff’s counsel disputed the defense examining physician’s testimony of how long the examination took, as well as plaintiff’s performance during the examination, suggesting the doctor was wrong based on counsel’s own personal knowledge. A plaintiff’s verdict was set aside and a new trial ordered for this, among other reasons; in fact, the reviewing court stated that “counsel’s conduct, together with the other errors set forth supra, denied the defendant a fair trial.” [Senn, 165 AD2d at 357, 567 NYS at 672.]

§27:92     Expert Bias or Interest

In the world of litigation as it actually exists, many experts tend to fall into the camps of either plaintiff or defense. It is appropriate to gently suggest that an expert may be “biased” in favor of defendants or plaintiffs if the greater percentage of his or her caseload is for one side or the other. The mere fact that an expert testifies frequently in litigation may suggest that the expert is “for sale.” [See, e.g.,McLain v. Lockport Memorial Hospital, 236 AD2d 864, 865, 653 NYS2d 774, 776 (4th Dept1997). (“The impeachment of plaintiff’s expert witness with evidence that he had testified in over 100 cases was proper.”).] Similarly, it is proper to bring out that the expert has worked with counsel or the client in the past, or that he or she has had substantial billings to counsel or the client in the instant or other cases.

Be careful not to go too far with this approach in the cross-examination or comments in the summation based on the cross-examination. [See, e.g.,Berkowitz v. Marriott Corp., 163 AD2d 52, 558 NYS2d 511 (1st Dept 1990) (comments that defense experts were “hired guns” were reprehensible); Chertok v. Effremoff, 226 AD 388, 389, 235 NYS 246, 247 (1st Dept 1929) (question to expert, “‘You know perfectly well for hire and for money you are down here to do all you can to try to show these two clients of mine guilty of malpractice, aren’t you’” was insulting and argumentative); Feaster v. New York City Transit Authority, 172 AD2d 284, 285, 568 NYS2d 380, 381 (1st Dept 1991) (“severely prejudicial” to elicit on cross-examination that defendant’s expert had previously testified as defendant’s expert in a similar case where the jury returned a verdict of $6 million; the court’s curative instruction for the jury to “ignore ‘some of the particulars that you may have heard just before’” was inadequate; and a new trial was required for this, among other reasons).]

§27:93     Impeachment by Inconsistent Statement

One reason why counsel should thoroughly examine an expert’s writings or statements in the instant case and in other contexts is to search for statements that could be considered contradictory to, or incompatible with, the expert’s testimony on the witness stand. Evidence of the inconsistency is not evidence of the truth of the inconsistency (although many jurors may think so); but the fact of the inconsistency itself, if not adequately explained, tends to reduce the believability of the witness.

Sweeping generalizations in prior statements are often useful; for example, an earlier assertion that it is impossible to derive opinions about how an accident happened without physically inspecting the accident scene (where the expert did not visit the scene of the subject accident); or a blanket pronouncement that a certain medical test should always be performed in given circumstances. [E.g., Garces v. HIP Hospital, Inc., 201 AD2d 615, 608 NYS2d 237 (2d Dept 1994) (once expert denied that an ENG test was warranted, it was proper to allow cross-examination using expert’s prior recommendation in another case that an ENG should have been conducted).]

The inconsistent statement may be by someone other than the witness if that person is part of the expert’s firm. [Carriage House Motor Inn, Inc. v. City of Watertown, 136 AD2d 8985, 524 NYS2d 930 (4th Dept1988) (the court did not err in admitting an earlier assessment of the property prepared by another member of the expert’s appraisal firm).]

In the federal courts and in most states, experts are routinely deposed before they appear at trial.  This is not the case in New York [See Ch 5]. However, depositions or trial testimony by well-traveled experts in other cases may be a fertile source for cross-examination. Of course, the testimony in the other case must be relevant; the more on all fours the previous testimony, the better. If the connection of the testimony is too attenuated, trial courts will not allow its use. [See Grasso v. Koslowe, 38 AD3d 599, 830 NYS2d 671 (2d Dept 2007) (trial court properly precluded during cross examination of expert the use of a deposition from an unrelated case in which the expert had previously testified).]


If the court excludes the inconsistent prior statement, be sure the statement is made part of the record. In Kahl v. Loffredo, 221 AD2d 679, 633 NYS2d 612 (3d Dept 1995), the Third Department was unpersuaded the trial court had erred in refusing to admit plaintiff’s expert’s prior written report where the report was omitted from the record, defendants did not satisfy their burden of establishing that the report was in fact inconsistent with the expert’s trial testimony, and defendants did cross-examine concerning the report’s omission of any reference to certain alleged negligence on the part of defendants.


An expert disclosure statement pursuant to CPLR 3101(d)(1) is not an “inconsistent statement” for purposes of attempting to impeach an expert. [Hageman v. Jacobson, 202 AD2d 160, 608 NYS2d 180 (1st Dept 1994). A 3101(d) disclosure statement is also not an appropriate basis for expert opinion when experts did not indicate they relied on it in forming opinions, and it is not the type of information expert opinion is properly founded on. [Hageman v. Jacobson, 202 AD2d 160, 608 NYS2d 180 (1st Dept 1994).] As they are not sworn, they are not judicial admissions. Thus, allowing expert disclosure statements into evidence is error, and if the prejudice of the improper admission of the statement is “sufficiently substantial [it may] warrant a new trial.” [Gibson v. St. Luke’s Roosevelt Hospital Center, 267 AD2d 136, 700 NYS2d 180 (1st Dept 1999); similarly, Veneski v. Queens-Long Island Medical Group, P.C., 285 AD2d 369, 727 NYS2d 105 (1st Dept2001) (new trials ordered in Gibson and Veneski).]

§27:94     Impeachment Through Learned Treatise

One effective tactic to attack an expert is by showing his or her position is contradicted by a “learned treatise,” i.e., a standard reference widely recognized as authoritative in its field. The rule in New York is that in order for the treatise to be used in this way, the witness must concede its authoritativeness. [People v. Feldman, 299 NY 153, 85 NE2d 913 (1949); Serota v. Kaplan, 127 AD2d 648, 511 NYS2d 667 (2d Dept1987); Mark v. ColgateUniversity, 53 AD2d 884, 385 NYS2d 621 (2d Dept1976).]

Counsel must at least be afforded the opportunity to ask the witness if he or she considers the reference authoritative. [Mark v. Colgate University, supra; Winant v. Carras, 208 AD2d 618, 617 NYS2d 487 (2d Dept 1994) (however, in Winant, the trial court’s error in sustaining objections each time plaintiff’s attorney attempted to confront an expert with respect to the authoritativeness of the Physician’s Desk Reference—PDR—did not warrant reversal, where the attorney was able to effectively cross-examine the expert using a different text which was conceded to be authoritative).]

If the witness does not accept the “treatise” as authoritative, counsel cannot resort to the expedient of reading questions that “clearly indicate[] to the jury that the statements which he read off his notepad were taken from those texts.” [Labate v. Plotkin, 195 AD2d 444, 600 NYS2d 144 (2d Dept 1993) (this technique was found to have unfairly prejudiced plaintiff, entitling her to a new trial).]

Reference to learned treatises not conceded as authoritative does not invariably lead to reversal. [See Golson v. Addel, 216 AD2d 268, 628 NYS2d 151 (2d Dept 1995) (use of PDR to impeach defendant’s expert where expert had not conceded PDR to be authoritative was harmless error under the circumstances); Rosario v. New York City Health and Hospitals Corp., 87 AD2d 211, 450 NYS2d 805 (1st Dept 1982) (where defense expert referred to the PDR on direct, it was proper for it to be used on cross-examination); Walsh v. Staten Island Obstetrics & Gynecology Associates, P.C., 193 AD2d 672, 598 NYS2d 17 (2d Dept 1993) (where objections to reading an article not conceded to be authoritative were sustained and counsel did not seek further relief, such as curative instructions, the issue was not preserved for review).]

Where an expert relied on a published article in his direct testimony, and said he agreed with a lot of what it said and that it was of value, he “could not foreclose full cross-examination by the semantic trick of announcing that he did not find the work authoritative.” [Spiegel v. Levy, 201 AD2d 378, 379, 607 NYS2d 344, 345 (1st Dept 1994). Compare Palma S. v. Carmine S., 134 Misc.2d 34, 509 NYS2d 527 (Fam Ct Kings County 1986) (which held that a doctor’s report not in evidence that was read by an expert but not relied upon may not be used to cross-examine the expert, the report in this respect being similar to learned treatises).]


If possible, avoid telegraphing your intent to use a learned treatise. Do not shove the treatise under the expert’s nose, opened to the specific page, with the passage highlighted in yellow, and simultaneously ask if the expert does not agree that the treatise is authoritative. Approach the subject somewhat more round-aboutly. Ask the expert to identify some of the authoritative texts in the field; if he identifies your treatise, you’re in. If he doesn’t, suggest three or four texts, of which perhaps you intend to use only one. (Parenthetically, if the expert smells a trap and disavows all the treatises, this has sent a different, but likewise negative, message to the jury, that he is out of step with the rest of the profession).


In the case of doctors who have performed independent medical examinations (IME) on your client, you or an assistant should have been present. Take the opportunity to note titles and authors of books on the doctor’s bookshelves. If the doctor denies the book is authoritative, ask him or her if it is not so, why is that very book, for which the doctor doubtless paid a considerable sum, found on a shelf in his or her office.


If a doctor disputes whether a given publicatiion is authoritative, you may or may not want to inquire as to the reasons why. But if the doctor says he has not heard of the publication so cannot accept it as authoritative, this may open up a whole other line of questioning, such as “You do keep up with the literature being published in your field, do you not,” “that’s part of a doctor’s job, to keep current,” and “if a doctor didn’t keep current, she wouldn’t be a very good doctor, would she?”  Pattern Jury Instruction (PJI) 2:150 suggests as part of a standard physician malpractice charge “every doctor is required to keep reasonably informed of new developments in (his, her) field . . .” [See Brazie v. Williams, 221 AD2d 993, 634 NYS2d 274 (4th Dept 1995) (medical malpractice can arise from a lack of knowledge).]

§27:95     Foundation for Impeachment Evidence

Care must be taken when asking an expert questions in an effort to “set him up” for impeachment by evidence to be presented later. The rules for using extrinsic evidence to impeach an expert are the same as for lay witnesses. For example, if the matter is “collateral,” counsel may not introduce extrinsic evidence and is bound by the expert’s answers. [See Ch 25. See also Golden v. General Motors Corp., 71 AD2d 717, 718, 419 NYS2d 211, 212 (3d Dept 1979) (“No proper foundation was laid to make the evidence admissible as a refutation of the plaintiff’s case”—court did not err in excluding certain physical evidence for purpose of impeaching plaintiff’s expert; “issue of impeachment was settled by certain responses of the witness on cross-examination and the evidence was properly excluded (Richardson on Evidence, Prince [10th ed.], §491) [now §6-305 in Prince Richardson, Evidence (Farrell 11th Ed. 1995)])”; Laken Realty Corp. v. State of New York, 79 AD2d 770, 435 NYS2d 64 (3d Dept 1980) (no error to preclude cross-examination of State’s expert about sales not used in either plaintiff’s or the State’s appraisal; claimant was attempting to use those sales as a form of supplemental appraisal, clearly inadmissible).]

[§§27:96–27:99 Reserved]

D.   Probing Foundation of Expert’s Opinion

§27:100   General Points

In all but the simplest cases, an expert will have, or should have, performed a fair amount of work to arrive at expert opinions. While some “expert” opinions are based purely on hypothetical questions, with the sole foundation being the expert’s education, experience, or innate brilliance, most experts perform at least a modicum of labor before arriving at their opinions, whether it be review of materials, research, examinations, experimentation or calculations.

In New York, the full extent of the expert’s preparation to give his or her opinions is almost never known before the expert testifies on direct—this despite the 1985 amendments to CPLR 3101(d) (requiring disclosure upon request of the facts and opinions the expert will testify to and a summary of the grounds for the opinions). Sometimes the full extent of the expert’s preparation is not disclosed even then—CPLR 4515 specifically provides that it is not necessary for an expert to present the foundation for opinions he or she states on direct. However, this same provision requires that the expert give the basis for the opinions if asked on cross-examination. The extent to which the expert elaborates or fails to elaborate on the technical basis for the opinion affects the weight that should be accorded the testimony. [Tarlowe v. Metropolitan Ski Slopes, Inc., 28 NY2d 410, 322 NYS2d 665 (1971). See also Nickerson v. Winkle, 161 AD2d 1123, 556 NYS2d 414 (4th Dept 1990) (trial court erred in failing to require plaintiff’s expert on cross-examination to specify the data, sources and other criteria for his opinion); People v. Watkins, 157 AD2d 301, 556 NYS2d 541 (1st Dept 1990) (cross-examiner is entitled to inquire as to basis of expert’s opinion, including exploring possibility of flawed test results, expert’s procedures, and expert’s knowledge of how variables can affect test results—this regardless of whether the examining party has expert evidence to the contrary).]

IN PRACTICE:          

Consider as your first two questions to the expert on cross, “Did you bring your file with you?” and “May I see it?” If the expert has file material with him or her, and you have a second chair, give the material to your second chair to review while you go on to something else; otherwise, wait for a break to look at the material yourself. If a recess is overdue, consider asking the court to give the jurors a rest room break to give you a chance to look at the file.

§27:101   Reliance on out-of-Court Material

CPLR 4515 permits expert opinion to be expressed without the necessity for stating the foundation; this sometimes results in the jury hearing opinions based on material that is not, and will not be, in evidence.

“If an opinion is given and cross-examination reveals it to be based on facts not in evidence, the opinion should be stricken.” [Lopato v. Kinney Rent-A-Car, Inc., 73 AD2d 565, 566, 423 NYS2d 42, 44 (1st Dept1979).] In Lopato, defendant’s medical expert admitted he had based his opinion in part on other doctor’s reports that were not in evidence. (The reviewing court noted the reports could have been placed in evidence with inadmissible material redacted, but this had not been done).

The absolute pronouncement in Lopato has been undermined by the exception stated in Hambsch v. New York City Transit Authority, 63 NY2d 723, 480 NYS2d 195 (1984), that an expert may rely on out-of-court material if it is accepted in the profession as reliable in forming a professional opinion [see Ch 15]; but if the reliability of the out-of-court material is not established, opinions based on it are still subject to being stricken.


Material not in evidence, but of accepted reliability, can also be used by the cross-examiner. [See, e.g.,Munoz v. 608–610 Realty Corp., 194 AD2d 496, 599 NYS2d 565 (1st Dept 1993) (since a report of plaintiff’s consulting surgeon was accepted in the medical field as reliable, defense counsel’s use of the report in cross-examining plaintiff’s treating physician was proper). But see Schwartz v. Gerson, 246 AD2d 589, 589, 668 NYS2d 223, 224 (2d Dept 1998) (even if doctor’s report was subject to the professional reliability exception, other plaintiff’s expert’s testimony went beyond this limited usage, where the report “constituted an expression of opinion on the crucial issue[s]” and plaintiff “with no risk of cross-examination of the doctor who prepared the report, was permitted to read the entire report to the jury”). Compare DiPrisco v. 2556 Boston Road Food Corp., 129 AD2d 411, 414, 513 NYS2d 683, 685 (1st Dept 1987) (records of attending physician had been excluded, although defendant’s doctor said some of his conclusions were based on them; on cross, defendant’s doctor said he agreed with the conclusion of the attending physician (which was that plaintiff may well have permanent disability), but when specifically asked if he held that opinion, said he did not think plaintiff would have permanent disability; trial court erroneously would not allow the witness to be confronted with the report, allowing the incorrect inference that the attending physician agreed with the defense expert: “[t]he unfair prejudice to plaintiff’s position inherent in this erroneous understanding seems to us to outweigh clearly the court’s effort to preclude the introduction of the opinion of a witness who did not testify …”; new trial on damages required); Vander Wel v. Palazzo, 155 AD2d 387, 548 NYS2d 14 (1st Dept 1989) (trial court erred in refusing to allow cross-examination as to doctor’s conclusion of a fracture dislocation based on hospital x-ray, where there was no mention of a dislocation in the hospital records).]

§27:102   Probing Foundation May Lead to Opinion Being Stricken

If probing the foundation of the expert’s opinion reveals it to be speculative or unworthy of belief, the opinion may be stricken.


  • Jackson v. Corgan & Balestiere, P.C., 132 AD2d 960, 518 NYS2d 530 (4thDept 1987). Expert testified a guard rail would have prevented a car going 30 mph from striking a building, but not a car going 50 mph; where the expert conceded he would need to know the force of the vehicle and the capacity of the proposed barricade to resist the force, but had done no such calculations or analysis, his opinion was wholly speculative and not admissible. Trial court properly dismissed the action.

  • Greek Peak, Inc. v. Grodner, 155 AD2d 827, 828, 547 NYS2d 944, 945 (3dDept 1989). In a non-jury trial to enforce restrictive covenant, plaintiff’s expert testified pole and antenna was capable of standing on its own, but on cross, when asked if the pole was free standing, said “no”; “This contradictory testimony is exacerbated by the fact that the expert’s only examination of the installation was from a distance of some 40 or 50 feet. He did not examine the brackets to the house, ascertain how, if at all, the pole went into the ground or determine if any concrete was used. Indeed, the witness conceded that whether the installation was freestanding depended on numerous factors, none of which he knew. “Such nebulous testimony is simply insufficient to satisfy plaintiffs’ burden of establishing the restrictive covenant by clear and convincing evidence.”

  • Andre v. Seem, 234 AD2d 325, 650 NYS2d 294 (2dDept 1996). Plaintiff’s expert had testified on direct that his opinion that plaintiff’s “serious injury” had been sustained in an auto accident was because plaintiff had denied any previous history of back problems. However, after it was established that plaintiff had been involved in a number of accidents before and after the subject accident and had complained in the past of back pain, the expert admitted that plaintiff could have sustained his herniated disc in any one of the prior accidents. Verdict of $480,000 for plaintiff was reversed and the complaint was dismissed.

§27:103   Methods of Attacking Foundation

There are several basic methods for calling into question the foundation of an expert’s opinions:

  • Challenge the expert’s methodology. [See §27:104.]

  • Bring out what the expert did not do. [See §27:105.]

  • Bring out what the expert does not know. [See §27:106.]

  • Probe the expert’s confidence level. [See §27:107.]

§27:104   Challenging Methodology

Question the expert in detail about all the work he or she did to arrive at the opinion. Pull out of the expert the precise procedures used to gather the data. For example, did the accident reconstruction expert personally take measurements at the accident scene, or did he delegate the task to subordinates? Did the real estate appraiser consider an adequate number of comparable properties in arriving at the appraisal of a piece of real property? Were these other properties truly comparable? What approaches did the business appraiser use in appraising the value of a business (did the appraiser compare different approaches, or rely upon only one?) Did the doctor personally examine the patient, or is the doctor simply relying on medical records? Did the testifying doctor review the x-rays personally, or is he or she simply trusting to radiologists’ reports? (Perhaps ask whether the witness doctor relied on the report because the radiologist who wrote it is more adept at reading x-rays than he is!) Did the mechanical engineering expert set up the equipment for the experiment, or if assistants did this, can the expert describe in detail the way everything was connected or positioned? (If the expert cannot, consider moving to strike testimony dealing with the experiment as lacking foundation.) Did the expert read the witnesses’ depositions, or did he or she just rely on summaries prepared by assistants, or by counsel?

Scrutinize the basic information the expert used to arrive at his or her opinion. For example, bring out that physician’s opinions are in part based upon a plaintiff’s subjective complaints. [E.g.,Glozik v. National Freight, Inc., 171 AD2d 977, 567 NYS2d 562 (3d Dept 1991) (expert opinion as to causation was diluted by testimony that for the most part, patient’s numbness could not be objectively confirmed and that neurological examination did not reveal nerve or muscle damage).] Note that cross-examination concerning the subjective nature of plaintiff’s complaints does not open the door to allowing a doctor to bolster his or her opinions by giving an opinion that plaintiff was not faking, malingering or exaggerating. [Kravitz v. Long Island Jewish-HillsideMedical Center, 113 AD2d 577, 497 NYS2d 51 (2d Dept1985).]

§27:105   Bring out What Expert Did Not Do

In contrast to challenging what the expert did do, bring out what the expert did not do that he or she should have. What factors did the expert fail to consider? Did the expert bother to go to the accident scene? If the expert did, where are his or her photographs, measurements, notes? (If the expert says he spent hours inspecting a product or an accident scene and yet made no notes, the adverse suggestion is obvious.) Did the expert take into account relevant statistics? Did the expert check pertinent data bases? Did the expert consult the standard references in the field? [See §27:94.] Does the expert even know what the standard references in the field are? Did the expert try different inputs to computer simulations of the accident to account for the possible ranges of physical variables (e.g., pavement coefficients of friction or differing angles of vehicle impacts)?

If the expert’s omission is sufficiently egregious, the court may strike the testimony as lacking foundation. [SeeOffice Park Corp. v. County of Onondaga, 64 AD2d 252, 409 NYS2d 854 (4th Dept 1978) (expert’s opinion was that certain improvements would have increased water flow; where cross-examination revealed that the expert had failed to take into account the amount of increase of water downstream, the area that drains into the area upstream, the effect of certain barriers or the amount of flooding that would have been prevented, the expert’s opinion was wholly speculative and not entitled to probative force); Pinto v. Pyramid Tire, Inc., 193 AD2d 723, 597 NYS2d 714 (2d Dept 1993) (tire expert did not take into account that one tire had been repaired twice, and did not test tires with a durometer, an instrument used to measure the hardness of a finished tire).]


Resist the temptation to ask the expert “why” he or she did not feel it necessary to consider this or that factor—the expert will doubtless offer an explanation that it was unimportant or irrelevant. If he or she is convincing, you have lost a potentially helpful point. Similarly, do not ask “why” the expert made no notes or measurements—far more experts will confidently assert that none were necessary than will look crestfallen and admit to an omission on their part. Instead, simply state the question as “you did not … (read the report) (make the measurement) (do the calculation), correct?” If possible, have your expert address the issue later (defendant in the normal course of putting on its direct expert case, plaintiff if an expert is used on rebuttal), or make the point in your summation.

IN PRACTICE:          

Do not get carried away and cross-examine about expert omissions that you as counsel forced on the other side. In DiMichel v. South Buffalo Railway Co., 80 NY2d 184, 590 NYS2d 1 (1992), counsel’s attempt on cross-examination to discredit the defense vocational expert for his failure to have examined plaintiff, where such an examination had been sought but was opposed by plaintiff’s counsel and prohibited by the trial court, was one error that contributed to depriving the defendant of a fair trial, and a new trial was required.

§27:106   Bring out What Expert Does Not Know

Some experts specialize in assisting counsel in litigation, handling hundreds of cases simultaneously, and have little time or inclination for in-depth preparation. Some experts who head large organizations delegate preparation to assistants, and rely on them to get up to speed to testify at trial. Sometimes such experts will not be deeply into the details of the research or calculations that went into opinions they happily subscribed to on direct.

Focus your cross-examination on the specifics of the expert’s analysis: the precise measurements of the accident automobile; the particular reference work; the unobtrusive nurse’s note in the hospital record. If you sense the expert’s knowledge of the case is shallow, continue to dig and make a point of highlighting each short cut or omission by incorporating it into successive questions.


  • Mohen v. Mooney, 205 AD2d 670, 614 NYS2d 737 (2dDept 1994). Where expert’s testimony was riddled with inconsistencies, it was incredible as a matter of law; and where plaintiff’s appraiser was unaware of plaintiff’s engineer’s observations when he made his assessment, no error to strike engineer’s testimony.

  • Cornier v. Spagna, 101 AD2d 141, 475 NYS2d 7 (1stDept 1984). Expert was effectively impeached by showing that he did not know that plaintiff had flown through the air before coming to rest on a grille.

  • Pinto v. Pyramid Tire, Inc., 193 AD2d 723, 597 NYS2d 714 (2dDept 1993). Expert who claimed tire had a defect in the vulcanization process did not know whether tire had been overcured or undercured.

  • Rodriguez v. Loreen Estates Co., NYLJ p 28, col 6 (Sup Ct,NY County, 12-9-96). Trial court harshly criticized a defense expert doctor as one of many “‘professional’ witnesses, grinding out ‘boilerplate reports’” who “prevent the expeditious resolution of meritorious cases,” where after the doctor had testified plaintiff had had no open reduction of the tibia, he was confronted on cross-examination with an x-ray clearly showing surgical insertion of a long plate and 14 screws, and “shamefacedly admitted his error and said he ‘hadn’t seen it!’”.

  • But see Leahy v. Allen, 221 AD2d 88, 91, 644 NYS2d 388, 390–91 (3dDept 1996). Court was not persuaded that expert’s testimony should have been stricken simply because opinions were based on observations “made under circumstances slightly different from those prevailing at the time of the accident.”

§27:107   Probe Expert’s True Confidence Level

Some experts express opinions to a “reasonable degree of certainty” on direct, but when pressed on cross-examination, hedge or backtrack from what sounded like absolute convictions. Any qualification to what seemed an unequivocal position will undermine the expert’s standing with the jury. If the hedging is sufficiently glaring, the court may strike the opinion; and if the opinion was the linchpin of the claim or the affirmative defense, that party’s case is placed in serious jeopardy.


  • Weber v. William & James Drugs, Inc., 199 AD2d 381, 605 NYS2d 375 (2dDept 1993). Plaintiff’s expert physician testified on direct that the child-plaintiff’s injury was permanent. On cross-examination, he admitted that the child had no current symptoms, he did not know if future treatment would be necessary or whether the child ever would exhibit symptoms, and that permanency of injury could only be determined after the child reached puberty. In light of this testimony, the trial court properly refused to submit the issue of permanency to the jury.

  • Knight v.Long IslandCollegeHospital, 106 AD2d 371, 482 NYS2d 503 (2dDept 1984). Where plaintiff’s expert pediatrician admitted that the degree of residual emotional problems would depend upon what treatment the child gets and how he responds to it, the award for future physical and psychological injury was excessive).

  • But see Board of Education v. Hueber, 90 AD2d 685, 686, 456 NYS2d 283, 284 (4thDept 1982). Expert on direct testified heating system was not designed in accordance with proper engineering standards because it did not include a heat recovery unit. On cross he was asked if failure to include the heat recovery unit was a “design error” or a “judgment call” and he answered “probably a judgment call.” This apparently contradictory statement did not diminish the legal sufficiency of the direct testimony, and it was for the jury to decide whether the architect’s omission was improper and actionable “as the witness’s testimony on direct indicated, or immune from suit, as his answer on cross-examination implied.”

§27:108   Handwriting Experts

“The competency of an expert witness who has expressed an opinion based on a comparison of writings may be tested on cross-examination by submitting other specimens of handwriting to the witness and asking him to compare them with the standard in evidence and to state whether they are in the same handwriting.” [Heller v. Murray, 112 Misc2d 745, 749, 447 NYS2d 348, 351 (NYC Civil Ct, Queens County 1981) (affirmed 118 Misc2d 508, 464 NYS2d 391 (App Term 2d Dept 1983)), citing Hoag v. Wright, 174 NY 36, 66 NE 579 (1903).]

§27:109   Turn Opposing Expert’s Testimony to Your Advantage

Once in a while, counsel may come across an “honest” expert, who testified on direct as he or she did simply because the expert did not have all the facts; and if additional facts are supplied on cross, the expert actually changes his or her opinion to support your position. In Glozik v. National Freight, Inc., 171 AD2d 977, 567 NYS2d 562 (3d Dept 1991), the jury’s verdict of defendant’s negligence not being a proximate cause of plaintiff’s injuries was upheld, where plaintiff’s experts modified their opinions as to causation when they learned on cross that plaintiff had had two prior accidents.

Admittedly, Glozik situations are few and far between. Most experts are firmly committed to supporting “their” side, and will try to avoid any admission that will aid the other side. While it is not realistic to hope that cross-examination will convince most experts to change their opinions, there may be opportunities to induce the expert to aid your cause in other ways. Sometimes, bringing out just a little more detail glossed over in the expert’s direct will serve. In Boulos v. State of New York, 56 NY2d 714, 451 NYS2d 725 (1982), plaintiff’s expert stated for the first time on cross-examination that the difference between the roadway superelevation where the accident occurred was only ¼-inch different from the required construction standard. Based on this testimony, the Appellate Division reversed the Court of Claim’s finding for plaintiff, and the Court of Appeals would not disturb the Appellate Division’s determination.


Even though actually getting an expert to change his/her opinion may be unlikely, sometimes it is worthwhile to ask the question anyway. In Feliciano v. Ford Motor Credit Co., 28 AD3d 221, 812 NYS2d 508 (1st Dept 2006), defendant’s argument that a surgeon’s opinion that a car accident caused plaintiff’s knee injury was based on the assumption that plaintiff had no prior knee injury, and plaintiff had undergone an X-ray for his knee four months before the accident, went only to weight and credibility, not to admissibility. “Notably, defendants never asked the surgeon whether awareness of the prior x-ray report would have changed his opinion. Thus, defendants benefitted as much as possible from their strategy and were not prejudiced.” [ 221-222, 812 NYS2d at 509.]

While additional information closely related to issues addressed by the expert may usually be brought in during cross, examining the expert on unrelated matters may be disallowed in the court’s discretion. [See Grcic v. City of New York, 139 AD2d 621, 527 NYS2d 263 (2d Dept 1988) (no error to restrict cross-examination of treating physicians with regard to opinion as to relationship between failure to use seat belt and injuries, since this issue was not gone into on direct, and defendant had the opportunity to call their own witnesses during their part of the case).]

§27:110   Admissions From Opposing Expert Can Lead to Dismissal

Most gratifying are occasions when testimony procured on cross-examination from an adverse expert so undermines the opposing party’s position that the opposing party’s case or defense is dismissed. While this rarely happens in this era of “professional witnesses,” it is not unheard of.


  • Vera v.BethIsraelMedicalHospital, 214 AD2d 384, 625 NYS2d 499 (1stDept 1995). In a psychiatric malpractice case, plaintiff’s expert’s admissions on cross that no psychiatrist does daily or weekly blood level readings of a certain drug administered to plaintiff, that the only way to determine if plaintiff had received a proper dose of the drug was careful clinical examination, and that the defendant doctor did perform such careful examinations, led to a plaintiff’s verdict being reversed and the case dismissed.

  • Evans v. Holleran, 198 AD2d 472, 604 NYS2d 958 (2dDept 1993). Where expert admitted on cross that he could not say with a reasonable degree of medical certainty that defendant’s departures from accepted medical practice were a proximate cause of plaintiff’s injuries, the trial court did not err in directing a verdict for defendant.

  • Weber v. William & James Drugs, Inc., 199 AD2d 381, 605 NYS2d 375 (2dDept 1993). Where plaintiff’s expert physician admitted that the child plaintiff had no current symptoms, he did not know if future treatment would be necessary or whether the child ever would exhibit symptoms, and that permanency of injury could only be determined after the child reached puberty, the trial court did not err in refusing to submit the issue of permanency to the jury.

  • Andre v. Seem, 234 AD2d 325, 650 NYS2d 294 (2dDept 1996). Plaintiff’s expert had testified on direct that his opinion that plaintiff’s “serious injury” had been sustained in an auto accident was because plaintiff had denied any previous history of back problems. However, after it was established that plaintiff had been involved in a number of accidents before and after the subject accident and had complained in the past of back pain, the expert admitted that plaintiff could have sustained his herniated disc in any one of the prior accidents. A verdict of $480,000 for plaintiff was reversed and the complaint was dismissed.

* EDWARD L. BIRNBAUM is the head of the Litigation Department at Herzfeld & Rubin, P.C. in New York. He is a prolific author of litigation articles and lectures frequently on litigation strategy and techniques for Bar Associations and Continuing Legal Education Institutions. His practice areas in litigation include personal injury, product liability, professional liability, commercial, strategy and trials.

Mr. Birnbaum was Chairman of the New York State Bar Association Committee on the Supreme Court, Chairman of the New York State Bar Association Action Unit No. 6; and a Member of the House of Delegates to The New York State Bar Association. He has served as an arbitrator for the American Arbitration Association, the United States District Court for the Eastern District of New York, and the Small Claims Division of the Civil Court of the City of New York. He has been an adjunct faculty member of New York University School of Continuing Education, teaching a course on the CPLR. He is a Fellow of The Roscoe Pound Institute, and a Fellow of the New York State Bar Foundation.

Mr. Birnbaum is the subject of biography in fifteen different national and international who’s who publications. He has the highest rating from Martindale Hubbell and he was named New York Super Lawyer in 2006. He received an LL.B Degree from New York University School of Law.

CARL T. GRASSO is a member of the firm of Herzfeld & Rubin, P.C. in New York City, specializing in litigation and trial work in the areas of personal injury, product liability and commercial litigation. For the past 27 years, he has been intimately involved in trials all over the United States, as well as in New York. He is an arbitrator in the Small Claims Division of the Civil Court of the City of New York. He holds Martindale Hubbell’s highest rating. He is a cum laude graduate of New York LawSchool.

Mr. Grasso also served in the United States Army, while in Vietnam in the Corps of Engineers, and later in the Judge Advocate General’s Corps. He has written for the Military Law Review and the Army Lawyer. He retired from the U.S. Army Reserve as a full colonel in 1996. His awards include the Bronze Star and the Legion of Merit.

JUSTICE ARIEL E. BELEN graduated from BrooklynCollege and Cornell University School of Law, where he earned a Doctor of Law degree with a Specialization in International Legal Affairs. Prior to his election to the bench in 1995, he served as a Supervising Attorney with the Criminal Defense Division of the Legal Aid Society. He later joined the New York City Law Department and served as the Bronx Borough Chief of the Office of the Corporation Counsel.

Justice Belen is a member of the Cornell University Council; Franklin H. Williams Judicial Commission on Minorities; Unified Court System Curriculum Development Committee; New York State Second Judicial District Uniform Rules Committee; and the Kings County Jury Board. He is a founding member of the Cervantes Society.

Justice Belen has headed the Trial Assignment and Jury Coordinating Parts in Brooklyn Supreme Court, on a rotating basis, since 1998.

In March 2005 Justice Belen was appointed an Associate Justice of the Appellate Term, for the Supreme Court for the 2nd and 11th Judicial Districts.

They are the authors ofNew York Trial Notebook,from which this article is excerpted.