Evidence of a person's other sexual misconduct is frequently admissible in sexual assault cases, child molestation cases, and in civil cases involving claims of sexual misconduct.

Fed. R. Evid. 901(b)(3) ("Comparison ... by expert witnesses with specimens which have been authenticated.").Handwriting or any other matter requiring authentication may be authenticated by having an expert witness compare the disputed handwriting or other matter with an authenticated specimen or exemplar and testifying that the author or maker of the disputed handwriting or other matter and the specimen or exemplar is the same person.

Fed. R. Evid. 414(b) ("In a case in which the Government intends to offer evidence under this rule, the attorney for the Government shall disclose the evidence to the defendant, including statements of witnesses or a summary of the substance of any testimony that is expected to be offered, at least fifteen days before the scheduled date of...In a case in which the prosecutor intends to offer evidence of other instances of child molestation under Federal Rule of Evidence 414, the prosecutor must disclose the evidence of such molestation to the accused, including statements of witnesses or a summary of the substance of any testimony that is expected to be offered, at least fifteen days before the scheduled date of trial unless the trial court for good cause allows disclosure at a later time.

United States v. Hadley, 431 F.3d 484, 495-496 (6th Cir. 2005) (upholding trial court's admission of wife's out-of-court statements to the police officers even though she was not called as a witness because "[the wife's]....The Sixth Amendment Confrontation Clause places no limits on the admission at trial of nonhearsay statements made prior to or outside of trial.