Let's be clear here that the majority opinion was far more nuanced than this article gives credit. The argument made in the original lawsuit against the DA's of

Let's be clear here that the majority opinion was far more nuanced than this article gives credit. The argument made in the original lawsuit against the DA's office was that the DA's office was failing to train its attorneys on the requirement to report exculpatory evidence (established by Brady v Maryland). However, they did not show that there was a pattern of failing to report such evidence at the DA's office, they just used the one instance and claimed, more or less, that it was obvious that the training was necessary. The Supreme Court case in question specifically addressed whether or not that was true—whether or not it was obvious that the training was necessary, and therefore whether it was a systemic problem that it was being left out. Scalia's opinion, which gets flak for citing Arizona v Youngblood, makes quite a few arguments, of which that is only one. It also brings it up solely to indicate that you can't train people in something that isn't actually true, something that was made untrue by that decision. The main thrust of his argument is that even if you could establish a pattern with a single violation in this case, there wasn't actually a violation at all, because the withholding of evidence was willful. Scalia also points out that the failure to train argument has to be applied carefully, lest it become something that every prosecuted individual can use to attack the municipality. These are all important distinctions because the Supreme Court generally decides the matter at hand. The case was about something very specific, and the justifications for awarding damages were also specific. The Court's task was to decide whether those justifications were valid, according to the law, not whether Thompson was morally wronged. If those things do not square with each other, then we have ways of revising the law or the Constitution to deal with it. But keep in mind that the verdict in the original trial was vacated after the evidence was discovered, and that the evidence was originally withheld intentionally by an attorney who died before the case was brought, and that the attorney who knew about it but didn't disclose it after the original attorney's death was sanctioned by the prosecutor's office. So this is all about what, if anything, Thompson deserved in compensation for the DA's office's errors, and there's a line to be tread there between compensation for mistakes and the acknowledgement that mistakes will be made by all human beings, and that burdening a municipality with dealing with all of them (particularly to the tune of several million dollars per case) might be unrealistic.