By promising not to prosecute Mr. Cosby, Mr. Castor was essentially letting him off the hook criminally so that he could be vulnerable to civil penalties. It is not the duty of a prosecutor to assist a victim in litigation strategy for a civil case. A prosecutor’s duty is to use discretion responsibly to make decisions about charges. Mr. Castor failed to use his discretion responsibly. The Pennsylvania court not only reversed the conviction, but it dismissed the case, precluding the prosecution from retrying Mr. Cosby without using his statements. Mr. Cosby may well have still been convicted without the use of his deposition testimony. We’ll never know. In the court’s view, the only just outcome was to protect Mr. Cosby’s rights by enforcing Mr. Castor’s promise. Even when a prosecutor believes the evidence is insufficient to file criminal charges, he rarely makes a public statement binding himself to that position because that situation is always subject to change. The possibility of obtaining more evidence of a crime makes a commitment against prosecution ill-advised. By overreaching to help the civil case, Mr. Castor blocked his successor from sustaining a conviction against Mr. Cosby. And Mr. Castor’s initial decision that the evidence was insufficient to prosecute may be his most egregious error.