10 Tips For Effectively Questioning an Expert Witness

Whether on direct or cross-examination, understanding the best questions to ask an expert witness is key. Questioning an expert witness differs in key ways from questioning lay witnesses. The heart of expert witness testimony is the expert’s opinion and the reasoning behind it – as well as the need to contextualize this opinion within one’s own case.

Here are some techniques for questioning expert witnesses on both direct and cross-examination:

On Direct

While popular wisdom holds that cross-examination is the true test of a lawyer’s skill, it is on direct examination that most lawyers are at a disadvantage. The inability to ask leading questions results in less control over the witness during questioning, making direct more demanding of good preparation and thoughtful questioning.

When anticipating direct examination of an expert witness:

1. Meet with your expert well before deposition or trial. By the time deposition or trial occurs, you should know your expert’s qualifications, opinion, and basis for that opinion inside and out. Meeting with your expert is the best way to ensure that you share a consistent understanding of the expert’s role in the process.
2. Outline your questions (don’t script them). Instead of writing out a list of questions you intend to ask, create an outline of the story you wish to tell through the testimony. Revise as needed until you have a solid final version. During direct examination, use this outline as a guide as you focus on creating a conversational rhythm with the expert.
3. Make the expert’s qualifications interesting. Whether or not you believe jurors rely on qualifications – or even remember them – establishing the expert’s qualifications is essential to their status as an expert. Good story-building skills come into play here as well: Start by choosing one of the expert’s more interesting accomplishments, such as an award or fellowship, and build qualifications from that point.
4. Lay the groundwork for the opinion. Before getting to the expert’s opinion, use short, precise questions to lay a foundation for the opinion. During this time, the expert should define key terms, explain processes, and so on. This “101” section of direct examination is essential for helping jurors understand the expert’s opinion. Work with the expert to keep terms and explanations simple and concise, yet accurate.
5. Use demonstrative evidence to illustrate, explain, or prove points. Teachers use visual aids regularly to help students understand material. The same technique can be used to help jurors understand an expert’s reasoning and opinion.
6. Summarize the expert’s opinion at the end of the testimony. End with a short summary that wraps up the key point: the opinion itself.

On Cross

Effective cross-examination requires developing strategies for probing expert witnesses to reveal inconsistencies or biases in their testimony. When preparing to cross-examine an opposing expert, dedicating a similar level of care to research and preparation is essential. The expert and the lawyer presenting the expert to the jury will know the expert’s background, opinion, and methods inside and out, and so should opposing counsel.

In anticipation of cross-examining an expert witness:

1. Use prior testimony to your advantage. A similar case in which the expert gave testimony that is contradictory to or inconsistent with their expected testimony in your case can be a powerful tool for cross-examination. Contradictory articles, blog posts, or similar publications can have a similar effect. Not only can these inconsistent sources undermine the witness’s credibility with the jury, they can even result in a judge declining to certify the witness as an expert.
2. Lay the groundwork during deposition. Cross-examination of a witness at trial is often won at the deposition stage. Focus on eliciting the exact opinions the expert intends to provide at trial, the specific basis for those opinions, and the details of the assumptions made in connection with that opinion. If trial testimony diverges in any way from the deposition, you have the chance to exploit those changes.
3. Develop a theory and use the expert report to execute it. Instead of simply using the expert’s report as an outline, first develop a theory to elaborate on cross-examination. Make this theory the “heart” of the story you tell through questioning. For instance, are you trying to tell the story that the expert made an honest mistake, is exaggerating on purpose, or is incompetent? By starting with the theory – and working from an outline similar to that used in direct examination – you can control the direction of cross-examination, instead of creating a repetition of direct by sticking solely to the expert’s report.
4. Throughout the process, stick to “yes” or “no” questions. Not only are experts typically well-versed in their fields, they come from fields that place differing values on concepts like knowing, evaluation, certainty, and doubt. Whether you’re attacking qualifications, addressing assumptions, or raising issues of bias, keep questions short, clear, and focused on eliciting a yes or no answer whenever possible.

Thorough preparation for questioning an expert witness pays off. Approaches for interrogating expert witnesses can provide the cornerstone for your entire case – or the means to undermine an opponent’s case entirely. By paying close attention to detail from preparation through examination, attorneys can ensure they use any expert’s appearance on the stand to their client’s best advantage.