expert-testimony-on-standIf you’re using expert witness testimony to support your client’s case, chances are good the other party is too. Each expert witness will be trying to poke holes in the opposing expert’s testimony. If you try to exclude or limit the opposing counsel’s expert witness testimony, the other party will try to do the same with your expert witness. What’s your game plan for this inevitable battle of the motions?


There’s an excellent article on the use of expert witnesses in patent litigation by two attorneys from the law firm of Perkins Cole, LLP.  The information applies to the use of expert witnesses in federal litigation in general, not just patent litigations. One section covers how and when to strike or limit expert testimony.

  1. 1.  Motion brought after expert witness report

According to the article, the up side of this approach is to possibly gain leverage over the opposing party early in the litigation process. But if the discovery is ongoing, you’re in the early stages of litigation and since excluding or limiting expert witness testimony is a fairly drastic step, the judge might allow the report to be supplemented.

2. Motion as part of summary judgment

A court may be more sympathetic to your argument in the later stage of the litigation process, after the opposing party has submitted its evidence, according to the article.  You can put the opposing party’s expert witness testimony’s deficiencies in the context of the case overall and contrast it with the testimony of your expert witness.  Even if your motion is denied, it may plant the seeds of doubt in the judge’s mind about the opposing party’s expert witness’ credibility, possibly impacting the decision on the merits of the case.

3. Motion in limine

This can be filed immediately prior to or during the trial.  The article states this may be the most common way to try and strike an expert witness’ opinion.  Since discovery has closed, there is little or no chance the court will allow supplementation, according to the authors. However, the judge may allow the jury to hear the contested expert witness opinion while reserving the court’s authority to overturn the verdict as a matter of law. The down side to this tactic is that is that briefing for these motions can take place after trial.  The judge’s view of the case may be colored by evidence introduced during trial or through the sheer force of the expert’s personality.

The authors advise attorneys to decide an approach based on the overall litigation strategy.

What’s been your experience with these motions to strike or limit expert witness testimony?  What advice would you give others on trying to limit expert witness testimony by the opposing party, while responding to these kinds of motions yourself?

By: Rodney Warner, J.D.