This essay, a version of the 2010 Tabor Lecture at Valparaiso Law School, examines issues about the role of a prosecutor in the adversary system through the lens of the following question: Should a prosecutor throw a case to avoid keeping men who he thinks are innocent in prison? This issue came to prominence in 2008, when Daniel Bibb, a New York City prosecutor, told newspaper reporters that he had done so in connection with a 1991 murder conviction that he had been assigned to reinvestigate after new evidence emerged that the wrong men had been convicted and were serving lengthy sentences. Bibb’s superiors required him (over his protests) to defend the convictions in a hearing to determine if the men should be retried. He had exhaustively...