Argument from the “anticanon,” the set of cases whose central propositions all legitimate decisions must refute, has become a persistent but curious feature of American constitutional law. These cases, Dred Scott v. Sandford, Plessy v. Ferguson, Lochner v. New York, and Korematsu v. United States, are consistently cited in Supreme Court opinions, in constitutional law casebooks, and at confirmation hearings as prime examples of weak constitutional analysis. Upon reflection, however, anticanonical cases do not involve unusually bad reasoning, nor are they uniquely morally repugnant. Rather, these cases are held out as examples for reasons external to conventional constitutional argument. This Article substantiates that claim and explores those reasons. I argue that anticanonical cases achieve their status through historical happenstance, and that their status is reaffirmed as subsequent interpretive communities avail themselves of the rhetorical resource the anticanon represents. That use is enabled by at least three features of anticanonical cases: their incomplete theorization, their amenability to traditional forms of legal argumentation, and their resonance with constitutive ethical propositions that have achieved consensus. I argue that it is vital for law professors in particular to be conscious of the various ways in which the anticanon is used – for example, to dispel dissensus about or sanitize the Constitution – that we may better decide if and when that use is justified.