Glossip v. Oklahoma

The prosecution's suppression of Sneed's psychiatric treatment records satisfied Brady's materiality standard because Sneed was the sole eyewitness to the critical fact—Glossip's alleged agreement to pay him to commit murder—and his credibility was the entire linchpin of the prosecution's capital case. Evidence of his mental health diagnosis and medication history would have provided powerful impeachment material that could reasonably have altered the jury's evaluation of whether this central witness was truthful about the crucial hiring arrangement. The prosecution's knowing elicitation of false testimony denying or concealing Sneed's psychiatric condition constituted a per se Napue violation requiring reversal independent of any materiality calculus. The combination of suppressed credibility evidence and knowing falsehoods, in a capital murder case resting entirely on a single informant's word, rendered the conviction constitutionally unreliable and demanded vacatur.