The purpose of the article is to offer a critique of the rule of reason, tracing its disintegration from its original articulation 100 years ago in Standard Oil Co. v. United States, 221 U.S. 1, 60 (1911). The article then describes a construct for restoring transparency and content to the rule of reason. The rule of reason is the default standard for assessing restraints under the Sherman Act. The role for the rule of reason has expanded in recent years as the Supreme Court has reversed a number of per se rules, thus relegating additional categories of restraints to the default rule of reason.