This Essay seeks to demonstrate that the interpretive use of standards in applying provisions of the Internal Revenue Code is not inconsistent with the rule of law. Part I discusses the relationship between rules and the rule of law and explains why we think so many tax scholars are drawn to a view of the tax law as consisting primarily of rules. We then demonstrate that the definition of income is properly understood as a standard. Part II addresses the descriptive dimension of this claim, summarizing and expanding our previous discussion of the definition of income to determine whether the term is susceptible to construction as a rule. We show that even a brief trip through some of the litigation required to determine whether certain items are income leads to the conclusion that the definition of income is not a rule. Part III addresses the normative dimension of our claim. There, we tease out the functions served by interpreting income as a standard and question where the interpretive authority lies with respect to the Code in order to argue that income ought to be treated as a standard. Part IV turns to several examples of what Professor Lawrence Zelenak regards as either a “disregard” or an “underenforcement” of the law to clarify our understanding of interpretation. We then conclude by observing that the Code does not “read itself”: Deciding whether a provision is itself a rule or a standard is itself an act of interpretation. Moreover, interpreting a provision as a standard is fully consistent with the rule of law