Territorial Leasing in Diplomacy and International Law focuses on an unexplored but relatively common practice in which states reallocate their rights on territory without altering formal boundaries or resorting to definitive cessions. As products of diplomacy, leases address a frequent situation that, in extreme cases, can lead to war: the desire by more than one state to exercise sovereign authority in the same place. As instruments of international law, they paradoxically reinforce the territorial integrity of states while raising questions about the nature of their sovereignty. This book draws from a large number of leases to examine the practice from historic to modern times, describing their elements in detail and assessing them from both political and legal perspectives.