This Article supports taking a deeper look at federal common law defenses’ applicability in immigration cases. On the rare occasions when noncitizens attempt to raise common law defenses, immigration judges tend to dismiss such defenses offhand simply because removal proceedings are technically civil, not criminal. Yet many common law defenses may be raised in civil cases. Additionally, immigration proceedings have become increasingly intertwined with the criminal system. After examining how judges already rely on federal common law to fill in gaps in the Immigration and Nationality Act (INA), this Article proposes three categories of removal cases that are particularly well-suited for raising federal common law defenses. The first category involves INA provisions that require conduct to be unlawful without requiring a conviction; the second category involves INA provisions barring asylum, which are closely connected to criminal culpability principles; and the third category involves certain removal grounds with no explicit mens rea requirement. Finally, the Article examines some of the legal and practical challenges to prevailing with these defenses in the removal context, drawing on criminal cases in which such defenses have been raised to immigration-related charges. The Article concludes that a more principled approach to the use of federal common law defenses in removal proceedings is necessary in order to promote consistent and fair adjudication.