Top 10 Mistakes Made by Expert Witnesses

Top 10 Mistakes Made by Expert Witnesses

So, you’ve found your expert witness, and you’re satisfied with their demeanor, credentials, knowledge, and appropriateness for your case. Now, it’s time to prepare for trial – submission of evidence, depositions, testimony, etc. – and prepare your expert with the fact patterns in your case.

However, there’s a more basic function you’ll want to perform as well, which is preparing your expert witness for the human crosscurrents present in any legal case, including nerves, aggressive questioning by opposing counsel, subconscious bias, familiarity with basic legal rules, and the like.

Below, our pros here at the Orion Expert Network (OEN) have provided a list of 10 mistakes frequently made by expert witnesses and how they can best be avoided. Please don’t hesitate to get in touch with us at with any questions or to request our assistance in your expert witness search process.

Don’t Be an Out-of-Control Information Firehose

When your expert witness is being deposed or providing testimony, it is extremely important that they not volunteer additional information that was not asked for. While it may be tempting to include information that the opposing counsel left out, the expert should only answer the question asked, and provide no additional information, other than to note if the framing of a question asked was unfair or potentially misleading. It is the job of an attorney, not the expert witness, to draw out this additional information if it is important. If the information is extraneous to the case, it could open up a whole host of problems and additional questions for you to deal with. Obviously, you’re not looking for your expert to add to the work you need to do.

Know When to Stop Talking

Along with the previous point, an expert witness should know how to be concise. Although a certain amount of detail and technical knowledge is probably required for adjudicating the case, it is certainly not necessary for the court to hear a graduate-level seminar on whatever topic the expert is there to discuss. While the best experts will have reams of information and endless ideas to share, it can be distracting and confusing for judges and jurors if they are overloaded with information. Work with your expert witness to keep their points tight and concise.

Don’t Be a Hedge Hog

What do courts want from expert witnesses? Specificity. Details. Certainty. Facts. What don’t they want? A whole lot of ‘maybes,’ ‘as far as I can tells,’ ‘apparentlys,’ et cetera. When an expert witness hedges their answers, it lessens their credibility and thus their effectiveness because they are not providing specific, concrete information. The court will need information to be as rock-solid as possible in order to render a competent decision.

So, even if your expert witness is at the top of their game professionally but has an awkward verbal tendency to use these types of hedging words, you will want to work to put it to the front of their mind not to use these words and instead stick to diction that indicates certainty. Certainly.

Serenity Now!

We’ve talked about civility in court, but to a degree, serenity is necessary as well (thanks Constanza). It’s no secret that during a trial or a deposition, opposing counsel may try to upset the expert witness in order to throw them off their game, causing them to answer questions incorrectly or in a huff and thus causing the expert witness to become flustered and get angry.

You will want to conduct a ‘murder board,’ or an intense practice session, where you prepare your expert witness for this type of questioning. The better that they are able to perform under these borderline abusive conditions, the less likely their testimony is to be affected by it. An expert witness whose credibility has been impeached due to inappropriate behavior or demeanor in the courtroom is likely a much less effective witness.

Not Complying with Court Orders

Just like you and your client and everyone else in the courtroom, the expert witness will need to play by the rules, which means that if they get subpoenaed and are asked to produce documents, they will need to do so in a timely fashion. As the attorney, if you believe such a request is unfair or overly-broad you will want to petition the court for assistance.

No Joke: No Jokes

Under. no. circumstances. Stick to the Laugh Factory.

One of the most important things about an expert witness is whether they are taken seriously, so any joking – even if it happens to be good – is going to reduce your witness’s effectiveness in promoting your case. So make sure they keep it professional at all times and don’t start joking back if the opposing counsel tries to bait them. There’s also the chance that a joke the expert perceives as funny might be found offensive by others in court – and so it’s best to stay as far away from this territory as possible.

When you have finished the case you can take your expert out to dinner and laugh all you want. (If they did a good job, of course.)

Guess What? No Guessing, Either

Just as the expert witness doesn’t want to use hedge words, because it impeaches their credibility, so too should they avoid guessing. Number one, if you’re using the word “guess,” you’re throwing lots of uncertainty into the minds of the people who are listening to what you’re saying. One of the things these people will probably be thinking is, “Does this person know anything for sure?” That’s not a good situation to be in in a fact-finding situation.

On that note…

It’s OK to Not Know Things – Just Make it Clear

If you’re unable to answer a question, feel free to say “I don’t know.” But then shut up. Elaborating is likely to lead to questions about other parts of your testimony. Pretending to know an answer when you don’t would be an even worse move, called perjury.

Lawyers Love to Talk – So Please Just Let Them

Don’t try to anticipate what counsel is going to ask and answer before they have finished. One reason for this is that it’s simply rude to interrupt someone while they’re talking, and the judge and jury will notice this. It is likely to inflame counsel as well, as lawyers love to talk and don’t particularly like to be interrupted by anyone, including the judge (although they do have to tolerate that). This sounds like a bit of a joke, but it isn’t. Ordinary human interactions can inadvertently take on weight during a trial, and you don’t want to be viewed as rude.

In addition, you’re not a mind-reader, and counsel may very well use your tendency to answer questions before their asked to draw out information and make a case that they might not otherwise be able to make. So if you wait until they’re done asking their question, you avoid this trap.

And finally…

Not Actively Listening at All Times

Even the most glamorous and fascinating trials, such as the OJ Simpson murder trial in 1994, are filled with plenty of long afternoons of very boring, routine, and droning questioning and presentations. If you happen to be working on a case such as this, make sure that you don’t allow the boredom to get to you and cause you to stop listening.

Not listening to counsel when you are being asked questions can cause you to answer incorrectly, which will damage your credibility and effectiveness, and it can also cause you to answer questions that you weren’t asked, which could reveal harmful information or help the opposing side make a case that your retaining counsel may not want to be made.

We at Orion Expert Network hope this helps and look forward to providing you any assistance you need with your expert witness search.

How to Prep Your Expert to Give Their Best Possible Testimony

How to Prep Your Expert to Give Their Best Possible Testimony

Here at Orion Expert Network (OEN), we like to provide a constant stream of up-to-date information and analysis, designed to help our clients and experts succeed prior to and at trial and beyond. [Once per week], you will find a new blog post at, providing information and advice on all aspects of the litigation and expert witness worlds.

Today’s post features OEN’s top six tips for experts about to take part in a deposition. Please let us know your thoughts, and feel free to add your own tips in the comments!


As an expert witness, the most effective way for you to provide excellent service to your client at all times is to maintain a laser-like focus on the issue or task at hand.

First and foremost, you should always be focused on telling the truth to the best of your ability. To do so, pay close attention to the questions opposing counsel asks you. If you don’t quite understand what you’re being asked, or if you don’t accept the premise of a question, don’t hesitate to say so.

And remember: it’s okay for you to say “I don’t know” when that is the honest answer.

Finally, be sure to fully think about the question before you answer it, so you can be as clear as possible.


Many depositions involve dozens or even hundreds of documents, adding up to hundreds or even thousands of pages. You should review in full detail any documents an attorney has made clear they will be asking you questions about. Although accommodations will likely be made for the review of documents as necessary during depositions, you won’t be able to provide a sufficiently precise and well-informed answer without looking over such documents beforehand.

Your prior review of these documents will also give you a useful perspective on the relative importance of information you may be asked for during the deposition. Many times, if an attorney is unable to get the answers they need on a major point, they will attempt to throw off the expert with a barrage of aggressive questions on a relatively minor point. If you are aware that such information is of less importance, any attorney hijinks are less likely to detract from your performance during the deposition.


As an expert witness, your strongest asset in a deposition is the knowledge you have of the relevant subject matter, which is often vastly superior to the present attorneys’.

Keep this in mind as you prepare, and try to anticipate what opposing counsel may attempt to throw at you to lessen your advantage here. For example, attorneys may arrange information chronologically in timeline form, or create charts and diagrams to present information in a certain way. If you prepare with these possibilities in mind, you’ll be better-able to push back against attorneys presenting information in an untruthful or misleading way.

Stay In Your Lane

Although sassy and smart-alecky witnesses are a staple of police procedurals like Law & Order, they’re not as beloved in the real-life legal world. Remember that you’re not a lawyer and to stay in your lane! This means you shouldn’t worry about things like why opposing counsel is asking a particular question, or allow yourself to become argumentative or emotional if the attorney tries to upset you or throw you off of your game.

If you happen to feel bullied or harassed by a lawyer, it likely means they’re upset by your strong performance, as they’re not getting the answers they want and need. Congratulations on a job well done!

Civility now

You can’t be an effective witness for your client if the judge and jury do not like you. We’ve already covered being honest, which is the number-one way to stay on their sides. But you should also strive to be respectful and answer civilly, even when opposing counsel is striking an unpleasant tone or being rude to you, and especially if they seem unprepared. No one likes an expert witness who rubs their superior knowledge in a faltering attorney’s face.

Oh, and if and when you are interrupted (and you will be), don’t get flustered. Wait for the interruption to end, and then politely ask to finish your statement.


As high-stress and anxiety-provoking as a deposition may seem, never forget at any point that you are a human being with basic needs that require your attention. Don’t hesitate to ask for a recess for a bathroom or snack break if you need one, even if it falls outside any previously agreed break schedule (when you gotta go, you gotta go!).

And remember that you’re not subjected to any sort of ticking clock during a deposition and that you can take your time to answer questions fully and accurately. If you need to go back and correct a mistake in your answers, or if you need your memory refreshed about a particular issue, just say so. The attorneys present will be happy to assist you.

If you or your firm have expert witness needs on any type of case, call OEN today at 617–528–0055 or email us at for help putting together your expert witness team. You do the rest. Let us worry about the experts.

By Orion Expert Network