In an important prosecutorial-misconduct case this term, the Supreme Court’s conservative majority threw out a $14 million jury award for a New Orleans man who was imprisoned for 18 years, including 14 on death row, for a robbery and a murder he did not commit. One month before John Thompson’s scheduled execution, a private investigator discovered that prosecutors had hidden evidence that exonerated him.

After his release, Mr. Thompson won a civil lawsuit against the Orleans Parish district attorney’s office, which had been led by Harry F. Connick, for its gross indifference to the incompetence of the prosecutors who violated his constitutional rights.

Justice Clarence Thomas, writing for the 5-to-4 majority in Connick v. Thompson, said the D.A.’s office was not liable for failing to train its lawyers about their duty under the Constitution to turn over evidence favorable to the accused.

The lawyers had kept secret more than a dozen pieces of favorable evidence over 15 years, destroying some. That failure to provide training, the court said, did not amount to a pattern of “deliberate indifference” to constitutional rights.