The relevance rule and the undue prejudice rule

Brown v. Bowen, 668 F. Supp. 146, 150 (E.D.N.Y. 1987) (plaintiff's mother, filed on her behalf a claim for surviving child's insurance benefits under the Social Security Act based on decedent's earnings record;....The best evidence rule is inapplicable -- the original writing or the original of another thing to which the rule applies -- need not be used to prove the contents of the writing or such other thing if the original is lost or destroyed through no bad faith of the proponent, the original is not obtainable, the original is in the opponent's possession and adequate notice that proof of the contents will be attempted, or the writing or other thing is not related to a controlling issue in the case.

Crawford v. Washington, 541 U.S. 36, 56 (2004) ("Most of the hearsay exceptions covered statements that by their nature were not testimonial--for example, ... statements in furtherance of a conspiracy.").If a statement is offered against a criminal defendant as the statement of the defendant's co-conspirator which was made during and in furtherance, the statement is not a "testimonial" statement for purposes of the right of confrontation guaranteed by the Sixth Amendment of the United States Constitution and the statement is therefore not subject to the constraints on admissibility imposed by that confrontation right on "testimonial" hearsay statements.

Cf. United States v. Giese, 597 F.2d 1170, 1190 (9th Cir. 1979) ("Unlike character witnesses, a defendant-witness may cite specific instances of conduct as proof that he possesses a relevant character trait such as peaceableness"; further: "Because character testimony alone may be enough to raise a...When an exception to the character evidence prohibition makes evidence of a criminal defedant's character admissible, the testimony of a witness on direct examination about the defendant's character must take the form of reputation or opinion and it cannot consist of specific instances of the defendant's conduct.