The concept of permissive law comes into play in several key passages of Kant’s writings in legal philosophy. Many scholars argue that Kant conceives of permissive laws as suspending moral demands, thus ‘permitting’ in the sense of tolerating morally wrong actions. In opposition to this view, this chapter submits that Kant takes permissive law to be a kind of moral licence. It lays the foundation of this interpretation through a reading of Kant’s discussion of permissive law in Perpetual Peace. As it argues, Kant follows Achenwall and Baumgarten in taking permissive law to be a species of prohibitive law, developing the concept of a law that specifies under which conditions certain actions are allowed. The function of the permissive law in Kant’s legal philosophy is neither to tolerate transgressions of prohibitions nor to regulate as such morally indifferent matters. As it shows, permissive laws are norms that specify under which conditions certain actions are allowed that would otherwise be forbidden. A permissive law licenses certain actions with respect to certain conditions. In the sphere of this licence, the actions are not merely tolerated, but genuinely permitted.