The Common Law of War

42 Pages Posted: 18 Apr 2016 Last revised: 23 Dec 2016

See all articles by Jens David Ohlin

Jens David Ohlin

Cornell University - School of Law

Date Written: April 12, 2016


In recent litigation before the federal courts, the U.S. government has argued that military commissions have jurisdiction to prosecute offenses against the “common law of war,” which the government defines as a body of domestic offenses, such as inchoate conspiracy, that violate the American law of war. This Essay challenges that definition, by arguing that stray references to the term “common law of war” in historical materials meant something different. By examining the Lieber Code, the writings of natural law theorists, and early American judicial decisions, this Essay unearths the following definition of the “common law of war”: a branch of the law of nations that applied during internal armed conflicts, such as civil wars with non-state actors. This body of law was called “common,” not because it was extended or elaborated by the common law method of judged-applied law, but rather because it was “common” to all mankind by virtue of natural law, and thus applied even to internal actors, such as rebel forces, who were not otherwise bound by international law as formal states. By recapturing this lost definition of the “common law of war,” this Essay casts some doubt on the U.S. government position that military commissions have jurisdiction, not only over international offenses, but also over domestic violations of the law of war.

Keywords: Common Law of War, Common Law, Lieber Code, Francis Lieber, Vattel, Natural Law, Quirin, Conspiracy, Non-State Actors

Suggested Citation

Ohlin, Jens David, The Common Law of War (April 12, 2016). 58 William & Mary Law Review 493-533 (2016), Cornell Legal Studies Research Paper No. 16-15, Available at SSRN:

Jens David Ohlin (Contact Author)

Cornell University - School of Law ( email )

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