There is no authoritative general definition of "testimonial."

Cf. Cooper v. Oklahoma, 517 U.S. 348, pin? (1996) (state requirement that criminal defendant establish his or her incompetence to stand trial by clear and convincing evidence violate federal constitutional due process guarantee; the Court's reasoning rests on the...The government can have the burden of proof on factual issues other than the essential elements of the crime charged and the government's burden of persuasion on such "collateral" issues can be and often is less than proof beyond a reasonable doubt. Conversely, sometimes a criminal defendant rather than the government has the burden of proof and persuasion with respect to factual issues that arise under legal rules and requirements apart from the essential elements of the crime charged; for example, a defendant may have the burden of establishing a defense such as duress.

United States v. Lopez, 340 F.3d 169, 175-177 (3d Cir. 2003) (reversing convictions for possession of heroin, and possession of contraband by an inmate because "the challenged statements constituted inadmissible hearsay,....Hearsay is a statement that (i) is made other than at the trial or proceeding at which it is offered and (ii) is offered to prove the truth of the matter asserted by the maker of the statement, the declarant.

United States v. de la Cruz-Paulino, 61 F.3d 986, 999 n. 9 (1st Cir. 1995) ("It cannot be doubted, however, that circumstantial evidence is often very probative. As Professor Wigmore notes, without allowing the introduction of evidence that permits 'an inference upon an inference,' 'hardly a single...Inferences based on inferences are permissible