There are exceptions to the adverse spousal testimony privilege, the marital testimony privilege

United States v. Zedner, 401 F.3d 36, 49-50 (2d Cir. 2005) (upholding trial court's admission into evidence of rebuttal witnneses' testimony about accused's previous commission of fraud, where accused claimed lack of criminal intent, and evidence of fraud was relevant to prove accused's "financial...Evidence of a criminal or wrongful act apart from the act that at issue at trial Is not barred by the prohibition against circumstantial use of character if intent, knowledge, mistake, or accident is a legally-material factual issue, the opposing party suggests the non-existence of knowledge or urges mistake or accident as a defense, and evidence of another crime, wrong, or act is offered to prove the knowledge or the absence of mistake or accident by a criminal defendant or other person.

United States v. Samet, 466 F.3d 251, 255-256 (2d Cir. 2006) (upholding trial court's admission into evidence of the inspector's testimony that autthenticated defedant's signature because "a lay witness who testifies as....A person's handwriting may be authenticated by a lay witness -- i.e., a lay witness may identify the author of handwriting -- if the witness is personally familiar with the putative author's handwriting and the witness did not acquire such familiarity for purposes of the litigation.

Cf. United States v. Washington, 498 F.3d 225, 230-231 (4th Cir. 2007) (upholding trial court's admission of the expert witness's testimony because no out-of-court statement was admitted into evidence through such testimony....A "statement" for purposes of the hearsay prohibition against the admission of hearsay statements is (1) an oral or written assertion or (2) nonverbal conduct of a person, if it is intended by the person as an assertion.