The U.S. Supreme Court lacks a jurisprudence for when courts should defer to immigration agency interpretations of civil removal statutes that involve criminal law terms or otherwise require analysis of criminal law. This Article represents a first step toward such a jurisprudence, arguing for an expansive principle of nondeference in cases involving ambiguity in the scope of crime-based removal statutes. The zone of nondeference includes not only statutes like the aggravated felony provision that have both civil and criminal application, but all removal grounds premised on a crime. The animating principles of Chevron U.S.A., Inc. v. Natural Resources Defense Council, Inc. as well as the rationales behind both the ban on deference to criminal prosecutors and the criminal and immigration rules of lenity all support the conclusion that courts should not defer to agency interpretations of crime-based removal grounds.