Prohibiting cross examination of a prosecution witness about his plea bargain violated the defendants right to confrontation under the Sixth Amendment. The undisputed head of a long-standing drug conspiracy entered into a plea agreement and subsequently testified against the defendant. The case hinged on whether the jury believed the testimony of the defendant or the testimony of his conspirator. The conspirators testimony could have led the jury to reasonably infer that he had no further reason to lie because he had already been sentenced, and that he did not expect to live to the end of his prison term because of medical problems. However, his plea agreement actually permitted a sentence reduction following his testimony, but although the defense was able to have the plea agreement admitted into evidence, counsel was not permitted to cross-examine the conspirator about the details. Specifically, the court prohibited the defense from asking the witness whether the prosecution would be the sole judge of whether his testimony was truthful for purposes of determining whether he was to obtain a sentence reduction. The Court of Appeals held that this limitation violated the defendants right to cross examination, and that because the case came down to a determination of credibility, the error was not harmless beyond a reasonable doubt.