Shannon v. United States

Summary

The Court held that the Insanity Defense Reform Act does not require a federal district court to instruct the jury about the consequences of a not-guilty-by-reason-of-insanity verdict, and that no such instruction is required as a matter of general federal criminal practice. The statutory text identifies the permissible verdicts but does not address consequences, and the legislative history cannot create a requirement untethered to the statute's text. The Court also rejected Shannon's supervisory-power argument because consequence instructions may confuse jurors and undermine the division between jury factfinding and judicial sentencing. Justice Stevens, joined by Justice Blackmun, dissented, arguing that defendants should be allowed to request the instruction to prevent juries from convicting based on mistaken beliefs about immediate release.