In Byrd v. Brishke, 466 F.2d 6 (7th Cir. 1972), the defendant officers failed to stop other officers who were beating plaintiff in defendants' presence. While intentional torts ordinarily require some affirmative conduct, purposeful nonfeasance can also serve as the basis of liability for an intentional tort if the defendant owes the plaintiff a duty to act. Thus defendants' failure to act in Byrd can be properly characterized as "intentional."