Shannon v. United States

Summary

Justice Thomas, writing for seven Justices, held that neither the Insanity Defense Reform Act nor general federal criminal practice requires instructing a jury about the consequences of a verdict of not guilty by reason of insanity. The statutory text does not require the instruction, and the legislative history cannot supply a requirement lacking a statutory reference point. Ordinarily, juries without sentencing responsibilities must decide guilt without considering the consequences of their verdicts, although a corrective instruction may be necessary when a witness or prosecutor misstates those consequences. The Court affirmed Shannon's conviction. Justice Stevens, joined by Justice Blackmun, dissented, arguing that defendants should be able to request an instruction to prevent jurors from convicting because they mistakenly believe an insanity acquittal means immediate release.