The law, Holmes said, is no brooding omnipresence in the sky. "If that is true," writes David Luban, "it is because we encounter the legal system in the form of flesh-and-blood human beings: the police if we are unlucky, but for the (marginally) luckier majority, the lawyers." For practical purposes, the lawyers are the law. In this comprehensive study of legal ethics, Luban examines the conflict between common morality and the lawyer's "role morality"...