The author offers a sketch of his thesis that legal principles are optimization commands. He presents this thesis as an effort to capture the structure of weighing or balancing and to provide a basis for the principle of proportionality as it is applied in constitutional law. With this much in place, he then takes up some of the problems that have come to be associated with the optimization thesis. First, he examines the objection that there are no such things as principles, but only different modes of the application of norms. Second, he discusses problems concerning the concept of an optimization command and the character of the “ought” contained in principles. He concludes that the distinction between commands to optimize and commands to be optimized is the best method for capturing the nature of principles.