Would the jury have convicted these men of murder if they’d known there was another suspect?

That was the pivotal question addressed by the Supreme Court in its Thursday decision to uphold the convictions of seven men in a high-profile murder case, even though the prosecution had withheld crucial information during the trial.

In his majority opinion, Justice Stephen Breyer called the case “factually complex,” but in the end, the Court determined, “It is not reasonably probable that the withheld evidence could have led to a different result at trial.”

This is the latest SCOTUS decision to focus on impact of suppressed evidence, instead of its mere existence, making it harder to get a new trial to challenge a conviction.

In Washington, D.C., in 1984, just a few blocks from the Supreme Court building, a 48-year-old mother of six named Catherine Fuller was found dead in an alley. She’d been beaten to death and sodomized with a pipe.

There was no physical evidence linking anyone to the crime scene. Prosecutors relied solely on witness statements to convict eight young men of first-degree murder. What the prosecutors didn’t disclose was that they had also identified another suspect.

The witness who found Fuller’s body saw two men in the alley. They both fled when the police arrived. The witness noticed one of the men hiding an object under his coat, and identified him as someone named James McMillan. The convicted men did not learn about McMillan until years later, when a journalist uncovered the evidence while investigating the case.

Before a trial, prosecutors are obligated to share any evidence that could acquit the defendant. It’s called Brady disclosure, after a 1963 Supreme Court case, Brady v. Maryland. There’s no standard to determine which evidence qualifies, leaving prosecutors with a tremendous amount of discretion.

A defendant can successfully challenge his conviction on Brady grounds if he can prove three things: that evidence was suppressed, that it’s favorable to him, and that it could have affected the outcome of the trial.

In the Fuller case, there was no doubt that favorable evidence had been suppressed, but would it have made a difference?

Justice Breyer stated in the opinion that the suppressed evidence was “too little, too weak, or too distant from the main evidentiary points to meet _Brady’_s standards.”

In her dissent, Justice Kagan pointed to the alternative theory the defendants could have presented with the evidence: “With the undisclosed evidence, the whole tenor of the trial would have changed … In my view, that could well have flipped one or more jurors — which is all Brady requires.”

The undisclosed suspect, James McMillan, went on to commit two nearly identical attacks on women and is now serving life without parole. One of the eight men convicted for the Fuller murder was let out on good behavior. Another died in prison. The other six have been incarcerated for the past 32 years.

One federal judge recently called Brady violations “an epidemic.” Out of the 762 murder exonerations listed in the National Registry of Exonerations, 50 percent were Brady violations. Brady is a second chance for the wrongly convicted, but the Supreme Court’s ruling limits its reach.