My dissertation investigates the effect of legal claims on the use of force, settlement, and third-party interventions in a territorial dispute. My main argument is that disputants act in the shadow of the enforcement that they anticipate from the rest of the international system. Third parties can enforce international law only when a violation is clear enough to coordinate against. A challenger's strong legal claim muddies the waters and weakens the enforcement that a violation should provoke. Conversely, a target's strong legal claim eases the coordination and facilitates enforcement. A challenger can use force as long as it is militarily capable and its legal claim is strong enough to keep third parties on the sidelines. International law does not operate only as a constraint independent of power; it allocates advantage, working as a license that military capability activates.

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The first half of the dissertation studies the disputants. Using an original extension of the Huth–Croco–Appel legal claims dataset covering 162 territorial disputes between 1945 and 2014, I find that legal claims operate differently on the two sides of a dispute. A target's stronger legal claim reduces the use of force against it. A challenger's stronger claim pacifies it near military parity but emboldens the challenger where its military advantage is clear. A parallel asymmetry governs settlement: a challenger's strong claim roughly doubles the annual odds that a dispute ends peacefully, while a target's strong claim roughly halves them. While the challenger's legal advantage pushes it to seek settlement or use force to resolve the dispute, the target's legal advantage does not purchase settlement; it purchases stalemate.

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The second half tests the enforcement logic. I theorize that third parties punish violations not out of a normative impulse toward restitution, but because states and international organizations that benefit from territorial stability rationally punish the violations that most threaten it. Drawing on an original intervention-level dataset of third-party diplomatic, economic, and military responses across 94 post-1945 disputes, I test when violations get punished. Preliminary results show that force used against targets with strong legal claims draws more frequent and more severe intervention, and case studies trace this enforcement in effect.

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