The Court often excludes experts who offer opinions regarding U.S. law itself—but there are some gray areas and circumstances where the Court has permitted such testimony. In patent cases, for example, the Court has typically excluded expert testimony about substantive issues of patent law, but has sometimes permitted experts to testify on PTO procedures (and sometimes not).
This week we got some more guidance, specifically in the context of a bench trial. In Upsher-Smith Laboratories LLC v. Zydus Pharmaceuticals (USA) Inc., C.A. No. 21-1132-GBW, the Court unsealed an order from last year …
