Ample evidence presented at the civil rights trial demonstrated that [DA] Connick's deliberately indifferent attitude created a tinderbox in which Brady violations were nigh inevitable."

Justice Ginsburg on the facts:

In Brady v. Maryland, 373 U. S. 83, 87 (1963), this Court held that due process requires the prosecution to turn over evidence favorable to the accused and material to his guilt or punishment. That obligation, the parties have stipulated, was dishonored in this case; consequently, John Thompson spent 18 years in prison, 14 of them isolated on death row, before the truth came to light: He was innocent of the charge of attempted armed robbery, and his subsequent trial on a murder charge, by prosecutorial design, was fundamentally unfair.

But for a chance discovery made by a defense team investigator weeks before Thompson’s scheduled execution, the evidence that led to his exoneration might have remained under wraps. The prosecutorial concealment Thompson encountered, however, is bound to be repeated unless municipal agencies bear responsibility—made tangible by §1983 liability—for adequately conveying what Brady requires and for monitoring staff compliance.

This was no isolated incident:

What happened here, the Court’s opinion obscures, was no momentary oversight, no single incident of a lone officer’s misconduct. Instead, the evidence demonstrated that misperception and disregard of Brady’s disclosure requirements were pervasive in Orleans Parish. That evidence, I would hold, established persistent, deliberately indifferent conduct for which the District Attorney’s Office bears responsibility under §1983.

The jury found for Mr. Thompson:

Having weighed all the evidence, the jury in the §1983 case found for Thompson, concluding that the District Attorney’s Office had been deliberately indifferent to Thompson’s Brady rights and to the need for training and supervision to safeguard those rights.

Four justices, like Judge Prado and a majority of the 5th Circuit Court of Appeals, got it right. But with one conservative too many on the Supreme Court, the wrongheaded view pervailed.