A. Engage As Consultant And Possible Witness.

Many times, experts are engaged first as a consultant and then the determination is made to disclose those experts as experts who will testify at time of trial. The key here is to realize that as long as the expert is a consultant, his work product is confidential. When the expert's name is disclosed as a potential expert in the matter, the prior work product becomes subject to discovery.

B. Explain Precisely Upon What Subject Matter The Expert Will Be Expected To Express An Opinion.

This is very important. Counsel should explain in detail to the proposed expert the exact issue or issues which counsel wants the expert to address. A determination should be made as to whether to limit the amount of information flowing to the expert. Counsel should remember that all information communicated to the testifying expert is discoverable. Counsel should attempt to narrow the focus of potential expert testimony but should also keep in mind that for the expert's testimony to be credible, he or she must be reasonably well-informed on any and all issues in the case which might relate to the basis or the ultimate opinion expressed by the expert.

C. Inform Expert Of What He Or She Is Expected To Do And On What Terms.

Counsel should define the scope of the expert's commitment of time. Counsel should provide the expert with the expected trial or deposition dates as early as possible.

D. Make Sure The Expert Understands The Scope Of Your Adversary's Discovery Rights.

The expert needs to understand that his file is completely discoverable. The following are important considerations which counsel and the expert should keep in mind.

1. Documents contained in the expert's discovery file should be those which counsel and the expert do not object to producing to opposing counsel.

2. The expert may want to be careful in putting preliminary opinions, impressions, or thoughts in writing. The expert should be reminded that putting preliminary opinions, impressions or other thoughts in writing makes those preliminary opinions, impressions or other thoughts discoverable and may also create a waiver with respect to any prior preliminary opinions, impressions or other thoughts.

E. Ethical Considerations -- How To Get An Honest Expert And Keep Him or Her That Way.

1. Hire the expert first as a consultant if possible and then decide whether to use him or her at trial.

2. Avoid experts who want to direct the case or seem to be attempting to tailor their answers to fit what they think you want. Such experts often lack credibility. Be very careful of the expert who wants to direct your case. Everything which is shown to your expert becomes discoverable. As a result, much of counsel's case could easily be subject to discovery by virtue of an overly aggressive expert attempting to review any and all items related to the case.

3. Let your expert know unequivocally that you want nothing but honest answers.


A. What To Give And What Not To Give To The Expert.

In short, counsel should only give to the expert those documents that counsel wants discovered.

B. The Importance Of Keeping Track Of What The Expert Has Reviewed Or Consulted In Reaching His Opinion.

Counsel must know what the expert has reviewed or consulted in order to make sure that the expert has examined enough material to provide a credible basis for his or her opinion and to prevent unintended disclosure of case materials.


A. Preparation In Common With All Witnesses.

Depending upon the experience of the particular expert, the expert should be advised that opposing counsel will attempt to illicit inconsistent testimony which will undermine the expert's credibility of the strength of the key opinion. All witnesses, and particularly an expert, should be told not to stretch beyond the truth, to rely only upon the facts which can be proven, and not to overstate his or her opinion. The demeanor of the expert may significantly affect opposing counsel's estimate of the persuasiveness of the expert, as well as the relative potential for success in the case. The expert should not argue with opposing counsel.

All witnesses, and particularly an expert, should be advised of the following with respect to answering questions:

(1) Listen carefully to the entire question. Do not answer the question until you are sure that you understand what is being asked. The expert should be reminded that many attorneys will deliberately ask misleading questions and that he or she should not attempt to answer a question unless the meaning is easily understood. The expert should not try to answer ambiguous questions. The expert should be very careful to avoid answering any question which mischaracterizes any prior testimony or misstates the facts.

(2) The expert should wait for a short time before beginning his or her answer to the question. This allows counsel the opportunity to object and allows the expert the opportunity to fully consider and formulate a thoughtful and considered answer to the question. The expert should be reminded that he or she should not allow opposing counsel to proceed at an uncomfortable rate. If opposing counsel asks the questions "rapid-fire", the expert should not allow this to cause him or her to rush.

(3) The expert should be reminded that he or she should not guess at the answer to a question.

(4) The expert should be reminded to answer only the question that is asked and to answer it as briefly and succinctly as possible.

(5) To the extent that the expert is aware of any mistake in his or her testimony, he or she should correct it before the end of the deposition after conferring with counsel. The expert should, accordingly, request a recess and should advise counsel of the mistake. Together, counsel and the expert should agree upon the best way to correct the record.

(6) The expert should fully review any document about which he is asked before answering any questions pertaining to such document. The expert should not assume that he or she is already sufficiently familiar with the document.

(7) The expert should be wary of questions designed to tempt him beyond the confines of his defined expertise.

B. Preparation Unique To Expert Based On Expected Lines Of Questions.

Experts should be prepared to deal with the following types of cross-examination:

(1) Attacks upon qualifications.

(2) Attacks upon the basis of the opinion. The expert should be fully aware of all of the facts upon which the opinion is based, should know which facts are significant such that a change in the facts would necessitate a change in the opinion, and should be fully prepared to describe all of the considerations entering into formulation of the opinion.

(3) Attacks based upon hypothetical or changed facts. This is an area where the expert should focus with counsel prior to the deposition. Counsel and the expert should go over each of the key facts to determine what changes in the opinion would have to be made given certain factual changes. What facts cannot be changed without destroying the opinion?

(4) Attempts to get the expert to agree with some or all of the premises of the opponent's case or of testimony by the opponent's expert.

The expert should be made fully aware prior to cross-examination of the key premises in the opposition's case. To the extent the expert is forced to agree to such a key premise, this may very well damage the viability of his or her own opinion and the overall success of the case. Where possible, the expert should be thoroughly prepared to avoid admitting any key premise of the opposition's case or of the opposition's expert testimony.


Deposing your opponent's expert can be one of the most important parts of your trial preparation. If you follow the method described below, it will also be one of the most effective ones.

1. Before the Deposition.

Before you can take the deposition of your opponent's expert you must find out who he is. Your local rules will tell you how to do this.

When you notice the other side's deposition, you should include a document request. In addition to the discoverable reports and writings that were requested in the demand for a witness exchange, you should ask for at least the following:

1. All documents reflecting or relating to any communication between the expert and opposing counsel, including such things as engagement letters.

2. All documents reflecting any communication relating to the engagement, including any communications with witnesses.

3. All documents reflecting or relating to any preliminary opinions or conclusions.

4. All documents consulted or relied upon by the expert in connection with the engagement including those he consulted or relied upon in forming his opinions.

5. All documents relating to his educational, employment, and professional history and any other documents reflecting or relating to his qualifications to testify.

6. Copies of all professional publications to that he has written or contributed to.

7. All documents reflecting other cases in which he has testified as an expert, including any documents, including transcripts, that reflect the substance of his testimony,Augu terms of his engagement, the court in which the action was pending, or the outcome of the case.

8. All other documents relating to the engagement, the opinions he expects to give, or the opinions he was asked to consider giving.

Before the deposition, you should learn as much as you can about your opponent's expert, his area of expertise, and the potential weak spots in his opinions. Your own expert is one source of such information but you should not limit yourself to any one source.

There are two schools of thought about whether it is better to try to take the deposition of your opponent's expert before or after that of your expert. If your expert goes last, your opponent will have had the benefit of seeing what a really good deposition of an expert looks like. He will also have a pretty good idea of your theories to help him prepare for his deposition of your expert. On the other hand, your expert will have the benefit of knowing what the other side's expert said and can avoid pitfalls and help you to develop lines of inquiry.

In the deposition, your goals will be to exhaust the witness's qualifications, his preparations to opine, and his opinions. In addition, you will explore with him all the areas that you expect to cover with your own witness, get any admissions you can, and explore any possible sources of bias.

You exhaust the witness's qualifications by first getting a narrative description of all of the qualifications and experiences that the expert believes qualify him to give an opinion in your case. Look for differences between the facts of this case and situations with which the witness has had experience. You should end up with a list of characteristics of this case with which the witness is unfamiliar or inexperienced. You can then use these admissions to exclude the witness's testimony or attack his credibility at trial with questions like "Isn't it a fact that you've never treated even a single person for a broken leg where there was also extensive damage to the kneecap?" or "You've never appraised a regional shopping mall before, have you?"

In addition, you should look for differences between the kind of opinion that the witness seeks to give at trial and the kind of opinion that the witness is required to form in his own work. For example, the branch manager of a stock brokerage firm who is being called to give an opinion about the suitability of an investment recommended by the defendant to the plaintiff may never be called upon to make ¾ eÄstment recommendations in his daily work of supervising other brokers and office operations. The goal with this kind of questioning is to limit the areas of the witness's expertise to exclude some or all of the areas material to the case.

As with all similar types of questioning, it is important to ask the closeout questions. For example, you should not leave the area of the witness's qualifications until you get an unequivocal "no" to a question like "Do you have any other qualifications or experiences that fit you to express an opinion in this case?"

After you exhaust the witness's qualifications, you do the same thing with respect to the witness's preparation to render an opinion. You want to know everything the witness did and should not leave this area until you get a satisfactory answer to your closeout questions. Then, get specific about what was not done. Ask the witness whether it would have been helpful to have done specific additional items of preparation. Ask whether the results of the additional procedures might have changed his opinions in any respect. Find out why or why not. Then ask the witness open ended questions about what additional preparation or procedures might have been helpful to him. Find out the reasons why or why not. Find out why any admittedly valuable procedures were not done. Ask the closeout questions.

Next you exhaust the witness's opinions. Find out all the opinions and conclusions he has reached or was asked to reach. Ask the closeout questions. For each opinion:

1. Find out all the facts upon which it is based. Find out the basis, if any, for those facts. Ask whether relevant alternative facts might result in a different conclusion. Find out why or why not. Ask the closeout questions.

2. Determine the witness's degree of confidence in each of his opinions in an attempt to distinguish between firmly held conclusions and mere guesswork or speculation. This works two ways:

a. If the witness admits that some of his opinions, conclusions, or assumptions are less than secure, his opinions will carry less weight.

b. If the witness claims an improbable degree of confidence in his opinions, he may hurt his credibility.

Finally, ask the witness all the questions you will or might ask your own expert. His opinion on many matters may support your theories and will be far more convincing on these points than those of your own witness. For each answer that contradicts your own expert or theory:

1. Find out the precise nature of the disagreement.

2. Find out whether the contradictory opinions are based on different assumptions. If so, ask whether the expert's opinion would change if he accepted the same facts as your expert. Ask him what other changes in the facts might change his opinions. If there are no facts that could change his opinion, or he says that obviously material facts wouldn't affect his opinions, he won't be very credible. If he admits that certain facts would change his opinion, maybe you can prove those facts at trial and turn him, in effect, into your witness.

3. Find out whether there is more than one school of thought in the community of experts. If so, see if you can get the hostile expert to admit that there is a substantial body of thought that supports your position.

During the course of completing the above lines of questioning, you should have gotten most of the useful admissions that could be obtained concerning the expert's expertise, preparation, opinions, and assumptions. In addition, try to get admissions concerning the expertise of your own experts and the reliability of any treatises, tests, or other sources of information upon which you intend to rely.

Next, you should ask the witness about the documents. Start by asking how the documents he brought with him or provided through counsel were gathered or selected. Ask about each category of document you requested and ask whether the witness knows of any documents in the category that were not produced. Also ask pointed questions about more specific kinds of documents that fall into the categories and that were not produced but that you believe or suspect exist.

Ask whether the witness reviewed any documents when he was preparing to testify, including personal notes, and make sure that you have copies of them. You should be aware that, while an argument can be made that many documents prepared by or reviewed by the witness are work product, cases in this area have held either that the designation of an expert to testify waives any work product or attorney-client privilege or that counsel's need to cross examine the expert on materials covered only by work product protection outweighs that protection. See, e.g., National Steel Products Co. v. Sup. Court (1985) 164 Cal.App.3d 477, 485, 488, 210 Cal.Rptr. 535, 540, 542; County of Los Angeles v. Sup. Court (1990) 224 Cal.App.3d 1446, 1458, 274 Cal.Rptr. 712, 720.

Finally, explore any possible sources of bias or interest. In particular, you should ask about the witness's relationship with the parties, with your opponent's counsel, and with the plaintiffs' or defendants' bar, and the terms

of the witness's engagement and compensation.


If you intend to try to prevent your opponent's expert from expressing an opinion, it may be better to do so by means of a motion in limine to try to avoid giving your opponent an excuse to present the witness's qualifications in exhausting detail and to avoid investing too much time before the jury in an effort that will probably fail. Assuming that the expert is allowed to testify, if your deposition was done properly, your cross examination will be easy, effective, and free of risk. Asking only questions that the witness has already answered in the deposition, you:

1. Bring out any limitations in the witness's qualifications and experience.

2. Elicit any limitations on the witness's confidence in his opinions and any unbelievable expressions of confidence.

3. Bring out any limitations on the preparation done and the additional work that the witness has admitted could have rendered his opinions more certain.

4. Elicit any damaging admissions concerning any issues in the case.

5. Elicit any assumptions that can be disproved or questioned. Alternatively, elicit the witness's assertions that no conceivable set of facts could have changed his opinions.

6. Elicit hypothetical opinions that support your theory. In the alternative, elicit the witness's assertion that his opinion would be unchanged even in a hypothetical case that obviously cries out for the opposite conclusion.

7. Bring out any admissions of the expert concerning the qualifications of your expert and the reliability of his sources, tests, and methods.

8. Save a good question for last.

A good last question is not an argumentative or conclusory one that will draw a valid objection or give the witness a chance to get the last word. A good question is a question that substantially helps your case, that is put in precisely the same terms as in the deposition, that was answered unequivocally in your favor, and the answer to which cannot be changed now by the witness without massive damage to his credibility. If you get the same answer you got at the deposition, SIT DOWN! If you don't get the same answer, remind the witness of the deposition, ask him whether he was under oath, ask him whether he was asked the previous question and gave the previous answer, and then sit down.


Counsel must make a determination of whether his or her expert needs to be rehabilitated on re-direct examination. When counsel is proceeding before the trier of fact, particularly a jury, counsel can demonstrate significant confidence in the testimony of his or her expert by choosing not to attempt to rehabilitate the expert. Also, attempting to rehabilitate your expert on a point which is not important, or on which his testimony is truly and unavoidably weak, may backfire by simply reinforcing the jury's perception of the weakness. Where the expert must be rehabilitated, counsel should confine re-direct examination to specific critical areas. The rehabilitation should be precise and efficient. Examining one's own expert on re-direct can afford your opponent an opportunity to revisit and reinforce your expert's weakest areas on re-cross if the re-direct examination is not carefully circumscribed.