In trial there may be nothing more challenging and dangerous than cross examining an expert witness. The lawyer about to cross examine an expert witness needs to be very careful and very well prepared prior to cross examining the expert. One of the problems that the trial practitioner encounters in attempting to effectively cross examine an expert is that the expert usually controls the testimony by being very knowledgeable in the area he is testifying about. What makes it more difficult is that the lawyer usually is not as well versed in the subject as the expert. Nevertheless, an attorney may successfully cross examine an expert witness by zeroing in on the weaknesses of the expert or of the expert’s testimony and exposing them to the jury. This may be accomplished many ways as will be discussed in this article. The first thing to do when preparing to cross examine an expert witness is to read and summarize the deposition taken of the expert witness or read and summarize prior depositions given by that same expert in other cases. You will probably find many helpful statements in the prior depositions that will assist you in your case. Additionally, research whether the expert has written any articles, books, editorials or the like that may contradict his opinion in your case. Next, determine what school the expert has graduated from and see if any of the professors that taught the expert have different opinions that may be introduced and compared to the expert’s opinion at trial. The trial attorney needs to be thoroughly prepared on the subject that will be the basis of the cross examination. I do not advise taking the expert “head on” within the expert’s field, but it is always very helpful to be quite knowledgeable in the area so that if the expert goes too far you may expose him as an advocate or as a hired gun. A trial attorney should always, always, always cross examine an expert witness. There is nothing worse then allowing an expert witness to give his opinions without challenge. The jury may believe that by failing to cross examine the expert you have accepted the expert’s opinion. Now, how should you begin cross examining an expert witness? The most effective way of beginning cross examination is to affect or attempt to affect the expert witness’s credibility. To do this, you should attempt to expose his bias. You should always be able to find bias. The expert witness will either be biased because of friendship, money or his relationship with the attorney or the attorney’s client. Bringing this out to the jury’s attention by using short precise leading questions will be very helpful. Attempt to point out, if possible, the disproportionate amount of time in court which the expert spends in comparison to the amount of time he spends in his given field of expertise. Additionally, point out the number of times that the expert witness has testified on behalf of the particular opposing lawyer or the lawyer’s law firm. Point out the number of times the expert has testified for parties that stand for similar things, for example, insurance companies, large manufacturers, big businesses, etc. After you have exposed the expert’s bias, you should attempt to attack his qualifications. No matter how qualified an expert witness may be in a given field, there are probably levels in his field that the expert has not reached. For example, if the expert witness only has a masters degree, you may point out that he lacks a Ph.D. in his given field (you should only do this if your expert has a Ph.D. in his given field). If applicable, you should point out that the expert witness has not published any articles in his learned field, or has not held any teaching positions in colleges or universities. Obviously, you need to discover this information before cross examining the expert witness. One way of learning this background information is by attaining the expert’s curriculum vitae or detailed resume well in advance of the trial. Another inexpensive way of attaining information on experts is by serving expert interrogatories on your opponent. See Florida Rules of Civil Procedure 1.280 (4)(1A); Federal Rules of Civil Procedure 26 (4)(A)(i). Another way of effectively cross examining an expert witness is by making the expert your witness. If you are able to have the opposing expert testify in general principles that are consistent with your theory of the case, you will have succeeded in your cross examination. This may be very difficult to accomplish, but if the expert is honest and if the questions that you are asking cannot be denied, you have a good chance of prevailing. If you ask an expert if the sun shines during daylight hours, when there are no clouds or rain and when there is no eclipse, chances are the expert will admit the sun usually shines. If you ask basic, helpful, leading questions that cannot be denied, the expert will have to admit the facts suggested in your question or appear foolish. Another way of successfully cross examining the expert witness is by attacking the expert’s facts. You will always be able to point out that the expert received his facts and materials from the opposing attorney. Use this to your advantage and use hypothetical questions in order to change the facts so that they are consistent with your theory of the case; then, ask the expert controlled questions within the restricted scenarios that you have presented. This will allow you to tell your version of the case through the opposing expert. Be very careful when you do this so as not to allow the expert too much room when testifying. You should present the hypothetical question in long detailed factual patterns followed by a direct leading question relating to the factually restricted hypothetical. Even if the expert refuses to provide you with a favorable response, you have told the jury your story repeatedly by using the hypothetical question. Another way to successfully cross examine the expert witness is by impeaching the expert witness with an article, journal or chapter of a book from his field. In your research, you will probably find positions and opinions that are contrary to the expert witness’s opinion. Attempt to have the expert witness agree that the author of the article in the journal, or the chapter in the book, or treatise is authoritative or at least a well recognized expert in the field. Next, identify the article or chapter, read the relevant portions that contradict the opinion of the expert, and then ask the expert if he agrees with the statement that you just read. It does not matter whether the expert agrees or disagrees, you have effectively demonstrated to the jury that other published experts do not agree with the opposing witness’s position. Finally, if you consider yourself to be extremely knowledgeable and an expert in the opposing expert’s field, you may attempt to directly attack him. WARNING – this is very difficult and dangerous. You should only attempt this if you are sure that you will succeed, or if the expert has made an obvious error in his investigation or in his calculations. Before attacking an expert “head on” you should confer with your own expert to make sure that the direct attack will be successful. Although there are many different examples of how to effectively cross examine an opposing expert offered in this article, you should only choose two or three areas of attack at trial. If you try all of them you will probably make the cross examination too lengthy or confusing. Moreover, the longer an opposing expert witness is on the stand, the greater the likelihood that the expert will hurt your case. Therefore, when cross examining the opposing expert, be prepared, be thorough, hit your two or three areas of attack, expose the expert’s weak points, then politely thank the expert and sit down.