Most practitioners would agree that, if the court excludes an expert based on a Daubert or Frye challenge—and that is the only expert opining on a subject—then in most instances there should be no need to proffer the expert’s testimony in order to preserve any potential error for appeal. But what if the court excludes only a portion of the expert’s opinion? Is a proffer necessary to allow for meaningful appellate review?

The court in American Automobile Ins. Co. v. Omega Flex, Inc., 783 F.3d 720 (8th Cir. Apr. 15, 2015), recently addressed this question in the products liability context. There, under Daubert, the court excluded a portion of the plaintiff’s expert’s opinion dealing with product design and warnings. Nonetheless, the expert testified at trial as to other opinions, such as causation of the house fire and the efficacy of the bonding of the propane gas pipes leading to the home.

On appeal, the plaintiff challenged the exclusion of a portion of the expert’s opinion.  The plaintiff, however, failed to submit a proffer of the additional testimony the expert would have offered had his opinion not been excluded.  As explained by the court, the plaintiff “made no attempt to explain what opinion testimony was excluded until pages 5-6 of its Reply Brief, where counsel articulated what [the expert] would have opined, without citation to the trial or appellate record. For this reason alone, the district court’s evidentiary ruling must be affirmed.”  Id. at 724.

In so ruling, the court affirmed the basic tenet that, where it is not contextually apparent, the failure to submit record evidence of what opinion the expert would have offered at trial precludes relief.

Preservation Issue:  Where any portion of an expert’s testimony is excluded, the failure to proffer what testimony the expert would have provided may result in waiver of a Daubert/Fryechallenge post-trial or on appeal.

Tip:  Even though you might think that the Daubert motion and hearing made it clear what evidence has been excluded, do not count on that. It will always be a good idea to proffer the testimony the expert would have presented had the opinion not been excluded.  In addition to preserving the record on this issue, there is always a chance that the court might revisit its ruling once the expert has testified. On a related note, where a court denies a Daubert/Fryemotion, consider a motion to strike at the conclusion of the expert’s testimony, again to give the court one last chance to rule in your favor.