In the case of Leland v. Oregon, 1951, the U.S Supreme Court upheld an Oregon law that required defendants pleading insanity as a defense to prove their insanity beyond a reasonable doubt. The defendant, Lawrence Leland Jr., was convicted for murder and sentenced to death in Oregon state court after failing to convince the jury he was insane at the time of his crime. He appealed on grounds that it violated his Fourteenth Amendment rights by placing an unfair burden on him rather than requiring prosecutors to disprove his claim of insanity. However, in a 5-4 decision led by Justice Felix Frankfurter, SCOTUS ruled against Leland stating that while most states placed this burden on prosecution (to prove sanity), there wasn't any constitutional reason why all states must do so.

In the dissenting opinion for Leland v. Oregon, Justice Jackson disagreed with the majority's ruling that upheld Oregon's insanity defense law. He argued that this law unfairly shifted the burden of proof from prosecution to defendant in cases involving an insanity plea. According to him, it violated a fundamental principle of justice: defendants are presumed innocent until proven guilty beyond reasonable doubt by prosecutors. In his view, requiring defendants to prove their own insanity was akin to asking them to establish their innocence - a reversal of standard legal procedure which he found unacceptable and unconstitutional under due process clause of Fourteenth Amendment. Furthermore, he expressed concern about potential misuse or misunderstanding of psychiatric evidence presented during trials as well as its possible impact on jury decisions.