This article questions the application of Chevron deference in federal court habeas review of statutory immigration detention challenges. Since the enactment of a mandatory detention statute for immigrants facing deportation, the Board of Immigration Appeals—an administrative body within the U.S. Department of Justice—has played an increasingly important role in interpreting the scope of detention for thousands of immigrants each year. Federal courts have long served as an important check against executive detention through habeas review and have declined to accommodate other deference norms in the immigration detention context. Federal courts have nonetheless applied Chevron to immigration detention cases without questioning whether such deference to the agency is appropriate. This article explains why federal courts should reject the application of Chevron when exercising habeas review of statutory immigration detention challenges. This article further explains that federal courts, whether or not fettered by Chevron, should apply interpretive norms that properly account for the important physical liberty interest at stake.