P's friend, Champy, was indicted for aggravated felonious sexual assault. P telephoned Mary Deary, who was acquainted with both P and Champy. May was the victim. P tried to get Mary to drop the charges. Mary complained that P was trying to force her to drop the charges against Champy. Mary told Chief Barrett that P had threatened that, if she went forward on the Champy case, she would 'end up like' two women who recently had been murdered in Lowell, Massachusetts. App. 49. Barrett arrested P and accused him of tampering with a witness in violation. P hired a good attorney who immediately told D to dismiss the charges or be sued civilly. They reached an agreement that if D would dismiss the charges, P would not sue the town. The agreement was presented to P, and eventually, P signed it, and the charges were dismissed. Ten months later, P filed an action under 1983 in the Federal District Court alleging that the town and its officers had violated his constitutional rights by arresting him, defaming him, and imprisoning him falsely. Ds filed a motion to dismiss, relying on the release-dismissal agreement as an affirmative defense. P argued that the agreement was unenforceable because it violated public policy. The court held the agreement to be valid. P appealed. The Court of Appeals for the First Circuit reversed. It adopted a per se rule invalidating release-dismissal agreements. The court stated: 'It is difficult to envision how release agreements, negotiated in exchange for a decision not to prosecute, serve the public interest. Enforcement of such covenants would tempt prosecutors to trump up charges in reaction to a defendant's civil rights claim, suppress evidence of police misconduct, and leave unremedied deprivations of constitutional rights.' The Supreme Court granted certiorari.