It should be noted that, in the context of a legal proceeding, “expertise” is both broader and narrower than the common usage. “Broader” in the sense that evidentiary law rigidly distinguishes between fact testimony, which for the most part is the testimony of people with personal knowledge of the facts, from expert testimony. As a result, the latter can include things like accounting, summarizing, or analyzing financial numbers to calculate damages.
On the other hand, the Supreme Court’s decision in Daubert v. Merrill Dow imposes the requirement that expertise be based on “reliable” methods. That would arguably exclude a number of academic discipline that aren’t based on such methods.