This brief essay, written for a symposium on The Emerging Interdisciplinary Cannon of Negotiation, describes three categories of rules which comprise the law of bargaining. First, common law limitations govern virtually all negotiators: the doctrines of fraud and misrepresentation limit the extent to which negotiators may deceive, and the doctrine of duress limits the extent to which bargainers can use superior bargaining power to coerce agreement. Second, context-specific laws sometimes circumscribe negotiating behavior in specific settings when general rules are less restrictive. Third, the conduct of certain negotiators is constrained by professional or organizational regulations inapplicable to the general public. These categories are discussed in turn. The final section of the essay reflects on constraints on negotiator behavior in the absence of law.