Chambers v. Mississippi
In Chambers v. Mississippi, 410 U.S. 284, 302-303 (1973), the U.S. Supreme Court guaranteed the right of a criminal defendant to present a complete defense in the following manner.
A murder defendant called as a witness a man named McDonald, who had previously confessed to the murder. When McDonald repudiated the confession on the stand, the defendant was denied permission to examine McDonald as an adverse witness based on the State's "'voucher' rule," which barred parties from impeaching their own witnesses. In addition, because the state hearsay rule did not include an exception for statements against penal interest, the defendant was not permitted to introduce evidence that McDonald had made self-incriminating statements to three other persons. Noting that the State had not even attempted to "defend" or "explain [the] underlying rationale" of the "voucher rule," this Court held that "the exclusion of [the evidence of McDonald's out-of-court statements], coupled with the State's refusal to permit [the defendant] to cross-examine McDonald, denied him a trial in accord with traditional and fundamental standards of due process."