Connick v. Thompson. Prosecutors withheld proof that the defendant was innocent. Defendant spent 18 years in prison, 14 on death row, before his lawyer accidentally found out about the suppressed evidence. Thompson sued the city, was awarded $14 million. Various appeals courts upheld the award.
Multiple courts, including the Supreme Court, ruled to be a clear violation of the defendant's constitutional rights, but the Supreme Court overturned lower court upholding the award and instead ruled, 5-to-4, that the city couldn't be held liable for prosecutorial misconduct. (The prosecutor already holds individual absolute immunity.) Clarence Thomas wrote that the city could not be held liable because the fact that its prosecutor blatantly violated the Constitution was not enough to make the city liable, unless it could be proved that its own specific policies had violated the Constitution.
In a similar case, they extended police immunity by ruling that a police officer couldn't be held liable for violation of a defendant's rights unless "every reasonable officer" working for the city would be aware of the issue, regardless of how gross the violation was. This continues a pattern of such bizarre rulings by the 5 "conservative" justices. (And a growing pattern of other court rulings. "Conservative" justices on California's supreme court just ruled that exercising your right to silence can be used as evidence against you, specifically a judge can use it to increase the severity of your sentence, unless you announce specifically that you are invoking the 5th Amendment each time you don't speak. Even if "exercising your right to silence" is simply not talking to the police until you get a lawyer, this can be used as evidence of your "callous disregard" by the court. (Note that this specifically goes against the argument behind the original "Miranda" ruling, which was based on the idea that people couldn't reasonably know their right to silence/lawyer/etc unless it was spelled out.))