The Federal Circuit’s decision in Kyocera Senco Industrial Tools Inc. v. International Trade Commission articulated a bright-line test for patent expert admissibility: to testify from the perspective of a “person of ordinary skill in the art” (POSITA), the expert must at least meet the definition of a POSITA for the patents-in-suit. Absent that level of skill, Kyocera holds that the witness’s testimony is not sufficiently reliable or relevant enough to be relied on by a fact-finder.