The Two Codes on the Use of Force

36 Pages Posted: 8 Jan 2016 Last revised: 31 Jul 2017

See all articles by Monica Hakimi

Monica Hakimi

University of Michigan Law School

Jacob Katz Cogan

University of Cincinnati - College of Law

Date Written: January 6, 2016


The jus ad bellum — the international regime that governs cross-border force — is an enigma. The regime is foundational to the global order and has been remarkably resilient over time. And yet, it is deeply discordant, even incoherent, in its operation. A few use of force norms are settled and robust. Although states occasionally deviate from these norms, the deviations are widely viewed and treated as legal violations. Other use of force norms are noticeably more compromised. Operations that stray from these norms are still perceived to be unlawful, but such operations might be tolerated or even supported in practice. Still other norms are highly contested. The norms’ substantive content is so openly and heatedly debated that the credibility of the entire regime has been called into question.

To the extent that the legal literature accounts for these features of the regime, it reverts to claims about what the law is or should be. This approach treats the disharmony in the jus ad bellum as either a function of the law’s ambiguity or evidence of states’ lawlessness — and thus as a problem to be solved. But the approach requires suppressing the very tensions and inconsistencies that shape the regime’s day-to-day operation. It therefore cannot account for how the regime actually works. And it has limited practical value to analysts who must plan for different eventualities, anticipate how varied actors will engage with the regime in concrete cases, or assess the impact of particular decisions on the regime’s long-term viability.

This Article takes a different approach. It aims not to advance a particular position on the content of the law but rather to present a positive theory that explains how the regime actually operates and why. What accounts for the combined resilience and disharmony of this regime? Why do different norms on the use of force display such varied characteristics? And how are specific norms likely to be invoked or applied in any given case? We argue that the regime on the use of force is constituted by two fundamentally different and competing visions of the legal order — two codes. Each code has its own substantive policies, decisionmaking processes, and key advocates. The way in which the two codes’ advocates interact in any given context determines whether and how particular use of force norms are articulated, invoked, or applied. Only by uncovering the two codes — and assessing their interactions — can we appreciate why the regime operates as it does.

Keywords: public international law, international legal theory, use of force, jus ad bellum, UN Charter

JEL Classification: K33

Suggested Citation

Hakimi, Monica and Cogan, Jacob Katz, The Two Codes on the Use of Force (January 6, 2016). U of Michigan Public Law Research Paper 490; European Journal of International Law, Vol. 27, p. 257, 2016; U of Cincinnati Public Law Research Paper No. 16-01; U of Michigan Public Law Research Paper 490. Available at SSRN:

Monica Hakimi (Contact Author)

University of Michigan Law School ( email )

625 South State Street
Ann Arbor, MI 48109-1215
United States

Jacob Katz Cogan

University of Cincinnati - College of Law ( email )

P.O. Box 210040
Cincinnati, OH 45221-0040
United States
513-556-0105 (Phone)
513-556-1236 (Fax)


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