The United States Supreme Court has extensively discussed the constitutionality of Federal Rule of Evidence 606(b) in only one case, Tanner v. United States, 483 U.S. 107, 97 L. Ed. 2d 90, 107 S. Ct. 2739 (1987). The two defendants in that case sought a hearing on jury misconduct based on juror affidavits that jurors were severely impaired during trial by alcohol and drug abuse. The defendants claimed that Federal Rule 606(b) deprived them of their Sixth Amendment right to a fair jury trial. the Court rejected the claim, noting the substantial policy considerations that support common-law rules against juror impeachment of verdicts in general, and Federal Rule 606(b) in particular. The Court went so far as to suggest that the jury system could not survive if courts permitted extensive post-verdict investigations into juries' internal deliberative processes. Id. at 120. Important to the Supreme Court's analysis in Tanner is its emphasis on the protection provided by other aspects of federal trial procedure. The Court noted that the suitability of a potential juror can be tested during voir dire, "jurors may report inappropriate behavior to the court before they render a verdict," and verdicts may be impeached post-trial by non-juror evidence. Id. at 127.