For over a century, immigrants have faced adverse immigration consequences if convicted of certain types of offenses in criminal court. Many types of criminal convictions carry severe immigration penalties, including deportation, detention, and the denial of status like asylum or U.S. citizenship. The Supreme Court recently recognized that these penalties are so intimately tied to criminal court adjudications that criminal defense attorneys have a duty to advise noncitizen defendants of the immigration consequences of their guilty pleas in criminal court. Yet there is little clarity as to how one determines whether a particular conviction triggers an immigration penalty. Historically, courts have applied a categorical analysis for assessing the immigration consequences of a criminal conviction. Under a categorical analysis, an immigration official determines the penalties based on an assessment of the statutory definition of the offense, not the factual circumstances of the crime. However, recent Supreme Court, federal court, and agency decisions have ignored this longstanding analysis and have instead examined these issues through the lens of Taylor v. United States, a criminal sentencing case that adopts a categorical analysis in a different context. Distinguishing Taylor and its criminal sentencing rationales, recent decisions have invented a new approach for how past criminal convictions are assessed in the immigration context that now permits a circumstance-specific inquiry into facts beyond the criminal court’s findings in some immigration cases. Under these recent decisions, the immigration consequences of a criminal conviction no longer turn on the criminal court adjudication alone, but may also account for facts that were not proven or pleaded in the criminal court proceeding. This article argues that this shift in analysis is based on a fundamental misunderstanding of the origins of categorical analysis in immigration law and its independent rationales, including its promotion of notice and an opportunity to be heard, uniformity, predictability, efficiency, and judicial review in the administrative agency context. The article further argues that, because of the flaw in the current debate, courts have failed to consider the negative impact that the erosion of categorical analysis has on the functioning of the current immigration and criminal justice systems. The rationales meriting categorical analysis apply with even greater force today than they did when categorical analysis was first articulated nearly a century ago.