Expert testimony is a feature of most IPRs, and effective expert testimony can make or break a party’s position. When evaluating expert testimony, the PTAB may consider several issues. First, are the expert’s qualifications sufficient? Second, even if the expert does not technically qualify as a “person of ordinary skill in the art,” should the expert’s testimony be given weight? The PTAB’s decision in Lupin Ltd. v. Horizon Therapeutics, Inc. (IPR2016-00829) addresses these questions and illustrates several ways to effectively use expert testimony.