The qualifications or characteristics necessary for a person to serve as a witness

Estelle v. McGuire, 502 U.S. 62, 69 (1991) ("The prosecution must prove all the elements of a criminal offense beyond a reasonable doubt.").The prosecution must establish each essential element of a criminal offense beyond a reasonable doubt.

United States v. Kennedy, 32 F.3d 876, 885-886 (4th Cir. 1994) (upholding trial court's admission of witness's testimony about accused's drug distribution activities because it was "proof of the existence and structure of the charged drug distribution conspiracy" which provided "the jury with background...Evidence that helps tell a factual story in an intelligible way or that puts the evidence or the issues in the case in a meaningful or intelligible context is "relevant."

Fed. R. Evid. 406 ("Evidence ... of the routine practice of an organization ... is relevant to prove that the conduct of the ... organization on a particular occasion was in conformity with the habit or routine practice.").The routine practice of an organization is admissible to show conduct on a specific occasion.