The convictions of two mentally disabled half-brothers were vacated and the two men were ordered released by Superior Court Judge Douglas Sasser in North Carolina on Tuesday. They were freed from prison Wednesday. Henry Lee McCollum, 50, had been on death row for 30 years, longer than anyone else in North Carolina history. He and Leon Brown, 46, who was serving a life sentence, were convicted for the 1983 rape and murder of an 11-year-old girl. DNA evidence implicated another man, a known sex offender the police had not investigated, despite the fact that he lived next to the crime scene. McCollum and Brown were 19 and 15 at the time local police were investigating the murder of Sabrina Buie. Both confessed to the crime after lengthy police interrogations. They recanted shortly after—in fact McCollum has recanted 226 times—but were convicted, largely on the basis of the false confessions, even though no physical evidence connected them to the crime scene. Police also hid exculpatory evidence for years.

A cigarette found at the crime scene now implicates a man who lived a block away from the soybean field where the girl’s body was found. He is currently serving a life sentence for a rape and murder that happened less than a month after Buie’s rape and murder.

The two teenagers signed confessions after hours of coercive police interrogation, under the erroneous belief that they’d be allowed to go home afterward. Both have since always maintained their innocence, filing various appeals over the intervening decades. It wasn’t until 2010, when the North Carolina Innocence Inquiry Commission came into the case, that the evidence was re-examined seriously. In July, the DNA on the cigarette butt found at the crime scene was revealed to match the DNA of the known sex offender. This led to Tuesday’s extraordinary release order.

This case highlights the same well-known and extensively documented problems that can lead to false arrests and convictions: Police who are incentivized to find any suspect quickly, rather than the right one carefully; false confessions elicited after improper questioning; exculpatory evidence never turned over; the prosecution of vulnerable, mentally ill, or very young suspects in ways that take advantage of their innocence rather than protecting it; prosecutorial zeal that has far more to do with the pursuit of victories than the pursuit of truth; and a death penalty appeals system that treats this entire screwed-up process of investigation and conviction as both conclusive and unreviewable.

The events in Ferguson, Missouri, last month reminded us to question whether there is ever a reason for the police to shoot an unarmed black teenager. The events in North Carolina should teach us to ask if there is ever a reason for the police to arrest, interrogate, and convict mentally challenged teenagers, without cameras, lawyers, or family present, and to ask how we can fail to correct a system that does so.

Why would two innocent people confess falsely? This always seems beyond imagining. Brandon Garrett of the University of Virginia School of Law has done extensive research on the question of why people confess to crimes they did not commit. In his study of the first 250 DNA exonerations for his book Convicting the Innocent, Garrett found that 40 of the 250 (or 16 percent) of the wrongful convictions happened when innocent defendants confessed to crimes they did not commit. (His updated data is here, showing that the patterns have held steady as the cases have increased.) As he reported in Slate in 2011:

Of those 40 exonerees who confessed, for instance, 14 were mentally disabled or borderline mentally disabled, and three more (at least) were mentally ill. Thirteen of the 40 were juveniles. All but four were interrogated for more than three hours at a sitting. Seven described their involvement in the crime as coming to them in a “dream” or “vision.” Seven were told they had failed polygraph tests. … Despite all these hints that their confessions were lengthy and coercive, and despite the fact that they were mostly vulnerable individuals, none had any luck challenging their confessions before trial. The confessions were thought to be such powerful evidence of guilt that eight were convicted despite DNA tests at trial that in fact excluded them as the culprit.

The false confessions from the North Carolina cases fit Garrett’s template almost perfectly. After five hours of questioning, as he listened to his mother weeping out in the hallway, McCollum offered up a story of attacking and killing the girl with three others. As McCollum said in a recent videotaped interview, he believed he would be released if he confessed and, “I just made up a story and gave it to them so they would let me go home.” Brown, once he’d been told his half-brother had confessed, and having been warned that he was facing capital punishment, also signed a confession.

The details in these confessions later horrified jurors. But as Garrett observes, if someone with an IQ that at one point tested at 49 is able to give such precise accounts, that should be its own cause for concern. “The level of granular detail shows that police shaped this confession statement,” he explains. “Police may have asked leading questions or outright fed facts. We now know McCollum and his brother were innocent and could not have known those details about the crime scene. They were not just coerced into saying ‘I did it,’ but they were coerced into repeating whole cloth an entire account of the crime, with details that only the police could have known, and not those vulnerable and innocent boys.”

The lack of any physical evidence linking the young men to the crime scene was no bar to their convictions. Fingerprints taken from a beer can at the scene did not match theirs. A local teen told the police she thought McCollum was involved, “because McCollum didn’t act right, riding a bicycle around staring at people, mostly women.” The two other suspects McCollum named were never charged with anything because there was no evidence. Lawyers for McCollum and Brown contend that local police hid boxes of crucial exculpatory evidence from the time of the trial in 1984. They were never turned over to defense lawyers or prosecutors.

Both McCollum and Brown, whose IQs usually test in the 50s and 60s, were originally given the death penalty. Both death sentences were overturned and then McCollum’s was reinstated after a second trial, while Brown was sentenced to life. As the New York Times notes, as recently as 2010, the North Carolina Republican Party featured McCollum’s booking photo on campaign fliers accusing a local Democrat of being soft on crime. The Times also points out that the defendants were prosecuted by Joe Freeman Britt, “the 6-foot-6, Bible-quoting district attorney who was profiled by 60 Minutes as the country’s ‘deadliest D.A.’ ” for seeking and getting the death penalty so often. (Britt told the Raleigh News & Observer last week that he still believed the men were guilty.)

One of the most infuriating things is that North Carolina at several points could have tested evidence known about years ago. We now know that three days before McCollum and Brown went to trial in 1984, local police asked the State Bureau of Investigation to examine a fingerprint on a beer can from the crime scene to see if it matched the man now implicated in the murder. The state didn’t bother. In 2006, Brown’s lawyers filed a motion to test the DNA on the cigarette butt. The results excluded both McCollum and Brown. But it wasn’t until several years later, when the state’s innocence commission got involved, that analysts found DNA on the cigarette butt matched up with the man convicted in the same neighborhood of a similar crime. Sharon Stellato of the commission testified on Tuesday that the man told her several times during interviews that McCollum and Brown were innocent.

It never fails to astonish me that the same conservatives who argue that every last aspect of big government is irreparably broken and corrupt inevitably see a capital punishment system that is perfect and just. If you genuinely believe that the state can’t even fix a pothole without self-dealing and corruption, how is it possible to imagine that police departments and prosecutors’ offices are beyond suspicion, even though they are subject to immeasurable political pressure to wrap up cases, even when the evidence is shaky and ill-gotten, and even as there are other avenues that have gone unexplored? Cops and prosecutors aren’t necessarily bad. But they are subject to political and community pressure that sometimes leads to improper conduct and the suppression of the evidence of that conduct.

Those who believe that we don’t execute the undeserving in America—or who aren’t too concerned about that possibility anyhow—have an ally in Justice Antonin Scalia. He famously insisted in Kansas v. Marsh that “”it should be noted at the outset that the dissent does not discuss a single case—not one—in which it is clear that a person was executed for a crime he did not commit. If such an event had occurred in recent years, we would not have to hunt for it; the innocent’s name would be shouted from the rooftops by the abolition lobby.”

That same Scalia, in an unrelated case before the Supreme Court 20 years ago, name-checked McCollum as the reason to continue to impose the death penalty. In that case, Callins v. Collins, Justice Harry Blackmun famously announced in dissent that he would no longer “tinker with the machinery of death” and would never again vote for the death penalty in any case. As Blackmun put it at the time: “The problem is that the inevitability of factual, legal and moral error gives us a system that we know must wrongly kill some defendants, a system that fails to deliver the fair, consistent and reliable sentences of death required by the Constitution.” In response, Scalia questioned why Blackmun hadn’t chosen a more grisly murder to make this announcement, specifically citing McCollum’s case as the more appropriate vehicle to announce that position. Scalia noted that all sorts of cases of truly horrendous murders came before the court, “For example, the case of an 11-year-old girl raped by four men and then killed by stuffing her panties down her throat. How enviable,” he wrote, “a quiet death by lethal injection compared with that!” Never mind that “quiet death by lethal injection” has little to do with how our executions are carried out these days.

When McCollum’s own case came before the high court, Scalia voted not to hear it. Blackmun again wrote a dissent from that decision, again chastising Scalia for failing to understand the stakes: “Buddy McCollum is mentally retarded,” he explained. “He has an IQ between 60 and 69 and the mental age of a 9-year old. He reads on a second grade level. This factor alone persuades me that the death penalty in his case is unconstitutional.” Interestingly, Blackmun never seems to have doubted McCollum’s guilt. He simply believed the man was mentally unfit for execution. What a difference a few decades of DNA exonerations make!

Several years after he baited Blackmun over McCollum, Scalia floated the notion that executing even innocents doesn’t violate the Constitution. After the court ordered a retrial in a controversial capital case, Scalia wrote for himself and Justice Clarence Thomas, that “[t]his court has never held that the Constitution forbids the execution of a convicted defendant who has had a full and fair trial but is later able to convince a habeas court that he is ‘actually’ innocent.”

It was once the case that McCollum was held out, to the collective members of the Supreme Court, as the very worst of the worst, deserving of death because of the heinousness of his crimes. Having shown that he never committed that crime, it seems high time to ask whether, in the view of some Supreme Court justices, that would have even made a difference had we executed him.