 Whatever else they do, all legal systems recognize, create, vary and enforce obligations. This is no accident: obligations are central to the social role of law and explaining them is necessary to an understanding of law’s authority and, therefore, its nature. Not only are there obligations in the law, there are also obligations to the law. Historically, most philosophers agreed that these include a moral obligation to obey, or what is usually called “political obligation”. For some, this is the consequence of some sort of transaction we enter with the state. Since states provide us with crucially important benefits, we incur certain duties in return, either because we consent to incurring these duties in exchange for the benefits, or because it would be unfair or ungrateful not to reciprocate for them. Other accounts are non-transactional in nature, and ground political obligation in the fact that obeying the law enhances our ability to do what we have reason to do, in the fact that we have duties to maintain just legal systems, or in special responsibilities qua members of our political community. All these lines of argument have been subjected to thorough criticism, and this has led some to deny that law is entitled to all the authority it claims for itself, even when the legal system is legitimate and reasonably just. On this view there are legal obligations that some of law’s subjects have no moral obligation to perform.