Skip to main content

What’s left out and why? Informal provisions in formal international law


When states face an international cooperation problem requiring enforcement, when do they decide to make that enforcement formal versus informal? I introduce a research design for investigating how informal mechanisms might be relevant to formal international agreements. I present an overall theory of punishment provisions and a set of hypotheses about whether any needed punishments will be formalized or not. This theory gives rise to a two-part empirical analysis conducted on a large-n dataset. First, the presence of enforcement mechanisms in agreements is predicted, and, second, those cases that are “misclassified”—ones in which the model predicts the presence of such mechanisms, but the agreements lack them—are analyzed. These misclassified agreements, candidates for informal enforcement, are characterized by regime heterogeneity and military asymmetries among parties. Case study evidence supports the results.

This is a preview of subscription content, access via your institution.

Fig. 1


  1. See Koremenos (2013).

  2. See Helfer (2005) as well as Koremenos and Nau (2010).

  3. See also Kleine’s (2010) particularly rich analysis of the EU presidency.

  4. See more on this point in the text below.

  5. See Koremenos’ (2001) case study on the NPT where the substantive articles were set in the first drafts while the duration provision was still being negotiated in the sixth year of negotiation. Koremenos (book manuscript) discusses both this assumption and the potential for the inability to incorporate the correct design provisions to have a feedback effect on agreement substance or, more likely, ratification.

  6. The precise conjecture is “Scope increases with the severity of the Enforcement Problem.”

  7. This is a variant of the Rational Design conjecture, Centralization increases with Uncertainty about Behavior (Koremenos, Lipson, Snidal 2001:787) since punishment is a task that can be centralized.

  8. The arguments above are consistent in spirit with two Rational Design conjectures: Flexibility increases with the Distribution problem and Flexibility increases with Uncertainty about the State of the World (Koremenos, Lipson, and Snidal 2001:793-4).

  9. Two other variables could influence the choice of formal versus informal punishment: renegotiation-proofness, i.e., is the delivery of the punishment in the interest of all states other than the defector ex post, and the targetability of sanctions, i.e., many agreements are best enforced through punishments in other issue areas, what Downs and Jones (2002: 107) call a “coercive linkage penalty.” I thank an anonymous reviewer for pointing me to this second variable. Both are addressed in Koremenos (book manuscript).

  10. Policies can then be tailored to the particularities of the subnational units.

  11. The argument here is that heterogeneity among participants affects the design of punishment provisions; in contrast, heterogeneity is assumed not to affect the likelihood that punishment provisions are required. Consider the example of the Prisoners’ Dilemma: the two actors are as alike as they can be in a game-theoretic sense; yet this homogeneity does not rule out the existence of an enforcement problem and hence the usefulness of punishment provisions.

  12. Cogan (2009) notes that informal law avoids explicitly acknowledging large differences in power and influence among participants to an agreement.

  13. This agreement is the “Convention on the prohibition of the development, production and stockpiling of bacteriological (biological) and toxin weapons and on their destruction” (UNTS 14860).

  14. As one anonymous reviewer noted, rewards should not necessarily be understood as irrelevant to agreement design just because we rarely see them incorporated formally as states sometimes negotiate stand-alone aid agreements that are closely associated with other agreements.

  15. COIL oversamples economic agreements because their population dwarfs the population in every other issue area; thus, within issue area variation in economics in terms of cooperation problems is substantial.

  16. The lack of significance on the variable Uncertainty about Behavior is consistent with Koremenos and Betz (2013) that this problem is best solved with information clarification, not punishment.

  17. The marginal effects of all of the cooperation problems are weakest for environmental agreements.

  18. If one compared the set of all misclassified agreements to the set of all other agreements, the results are slightly stronger than the results reported here.

  19. All of the data was drawn from Norris (2009).

  20. I thank an anonymous reviewer for this excellent point.

  21. Importantly, detected noncompliance in the domestic law context does not always result in punishment. I have received only two speeding citations since I began driving but substantially more than two warnings. My spouse has a less fortunate ratio of warnings/citations, illustrating that heterogeneity in “regime type” matters in this context as well, with police officers using discretion regarding how and how often to punish depending on the individual characteristics of the offender.

  22. Szasz (2002).

  23. The NPT is not in the COIL random sample and thus not on the list of misclassified agreements.

  24. In the case of world sanctions against South Africa for its apartheid regime, it has been argued that the actual Convention against Apartheid had little to do with the outcome. (I thank an anonymous reviewer for this point.) Although counterfactuals are challenging to argue, in the Apartheid case, given that most powerful states (like the US and almost all of the Western European states) remain outside the Convention, it is clear the formal agreement is not playing a large role. Still, apartheid is prohibited in other international agreements that have been ratified by great powers like the US and the UK—e.g., the International Convention on the Elimination of All Forms of Racial Discrimination (ICERD). (And Article 3 of ICERD, which contains the prohibition, does not have reservations attached to it.)

  25. Some might argue that North Korea is no longer a member of the NPT, but its status is open to interpretation given its unconventional (and most likely unlawful) withdrawal. In 2003, North Korea withdrew with only a one-day notice, citing that it had already fulfilled the balance of the official 3-month notice period when it gave notice of withdrawal in 1993, a withdrawal that it subsequently suspended. In any event, during the period when the rewards and sanctions discussed below were part of the picture, North Korea was most certainly a member of the NPT.

  26. Libya dismantled its program to the satisfaction of the major powers prior to the collapse of the regime.

  27. Dorn and Fulton (1997).

  28. Dolley and Leventhal (2001).

  29. Ibid.

  30. Ibid.

  31. UNSC Resolution 687 suspended the use of force in Iraq under the condition that Iraq fulfills its UNSC obligations, and included in that is Iraq’s obligations under the NPT (see paragraph 11). The Resolution states: The UNSC became “Concerned by reports in the hands of Member-States that Iraq has attempted to acquire materials for a nuclear weapons programme contrary to its obligations under the Treaty on the Non-Proliferation of Nuclear Weapons of 1 July 1968,” "Security Council Resolution 687." UN News Center. United Nations, n.d. Web. 09 Oct. 2012,

  32. The Guardian, “Syria Nuclear Weapons Site Revealed by UN Investigators,” The Guardian via Associated Press in Washington, November 1, 2011, Available at . Last accessed on October 11, 2012.

  33. Flemes (2006).

  34. Nedal (2011).

  35. The German case has ceased to be a problem (see below) in part thanks to US pressure.


  37. Bajoria and Pan (2010).

  38. Richter, Paul. "U.S. Feared a Nuclear Argentina." Los Angeles Times. Los Angeles Times, 23 Aug. 2002. Web. 9 Oct. 2012.

  39. Remarks made at the Institute for Science and International Security; see

  40. Agreements were reached with Germany and through the IAEA that placed restrictions on German aid in helping develop Brazil’s nuclear capacities (Nedal 2011).

  41. Resolution 1547, from June 11, 2004, “condemn[s] all actions of violence and violations of human rights and international humanitarian law,” but introduces no punishments beyond the shaming inherent in condemnation. UN Security Council, Security Council Resolution 1547 (2004) on the situation in Sudan, 11 June 2004, S/RES/1547 (2004), available at: [accessed 18 August 2012]. Concrete punishments were introduced on March 27, 2005. UN Security Council, Security Council Resolution 1591 (2005) on Sudan, 29 March 2005, S/RES/1591 (2005), available at: [accessed 18 August 2012].

  42. UN Security Council, Resolution 1132 (1997) Adopted by the Security Council at its 3822nd meeting, on 8 October 1997, 8 October 1997, S/RES/1132 (1997), available at: [accessed 18 August 2012].

  43. UN Security Council, Security Council resolution 1970 (2011), 26 February 2011, S/RES/1970 (2011), available at: [accessed 18 August 2012].

  44. UN Security Council, Security Council resolution 2009 (2011), available at: [accessed 18 August 2012].

  45. Future research should examine why the UNSC rarely, if ever, cites specific treaties and whether the permanent members have opinions on the topic based on their own ratification status.

  46. De Klemm (1993).

  47. Memorandum by Secretary of State Cordell Hull to President Roosevelt, Washington, DC, March 30, 1944. Available at Accessed on August 18, 2012.

  48. See Koremenos (2013) for an overview.


  • Abbott, K. W., & Snidal, D. (2000). Hard and soft law in international governance. International Organization, 54(3), 421–456.

    Article  Google Scholar 

  • Aust, A. (1986). The theory and practice of informal international agreements. International and Comparative Law Quarterly, 35(4), 787–812.

    Article  Google Scholar 

  • Axelrod, R. (1984). The evolution of cooperation. New York: Basic Books.

    Google Scholar 

  • Bajoria, J, & Pan, P. (2010). The U.S.-India Nuclear Deal. Council on Foreign Relations, available at Last accessed on October 11, 2012.

  • Chayes, A., & Chayes, A. H. (1993). On compliance. International Organization, 47(2), 175–205.

    Article  Google Scholar 

  • Chayes, A.H., Chayes, A., Mitchell, R.B. (1995). Active compliance management in environmental treaties. In: W. Lang (Ed.), Sustainable development and international law, Chapter 6 (Graham and Trotman Ltd.).

  • Cogan, J. K. (2009). Representation and power in international organization: the operational constitution and its critics. American Journal of International Law, 103(2), 209–263.

    Article  Google Scholar 

  • De Klemm, C. (1993). Biological diversity conservation and the law: Legal mechanisms for conserving species and ecosystems. Environmental Policy and Law Paper No. 29 (IUCN – The World Conservation Union).

  • Department of State. Briefing paper on human rights. National Archives, RG 59, L/HR Files: Lot 80 D 275, Human Rights S/P Study—Policy Planning Vol. II. Confidential. Available at Last accessed on October 11, 2012.

  • Dolley, S., & Leventhal, P. (2001). Overview of the IAEA nuclear inspections in Iraq. Nuclear Control Institute, June 14, 2001. Available at Last accessed on October 11, 2012.

  • Dorn, W., & Fulton, A. (1997). Securing compliance with disarmament treaties: carrots, sticks, and the case of North Korea. 3, 17-40.

  • Downs, G. W., & Jones, M. A. (2002). Reputation, compliance, and international law. Journal of Legal Studies, 31(1), 95–114.

    Article  Google Scholar 

  • Downs, G. W., & Rocke, D. M. (1990). Tacit bargaining, arms races, and arms control. Ann Arbor: University of Michigan Press.

    Google Scholar 

  • Downs, G. W., & Rocke, D. M. (1995). Optimal imperfection? Domestic uncertainty and institutions in international relations. Princeton: Princeton University Press.

    Google Scholar 

  • Ehrlich, I., & Posner, R. A. (1974). An economic analysis of legal rulemaking. Journal of Legal Studies, 3(1), 257–286.

    Article  Google Scholar 

  • Flemes, D. (2006). Brazil’s nuclear policy: from technological dependence to civil nuclear power. Working Paper, GIGA Research Program: Dynamics of Violence and Security Cooperation. Hamburg, Germany: GIGA.

  • Goldstein, J. O., Kahler, M., Keohane, R. O., & Slaughter, A.-M. (2000). Introduction: legalization and world politics. International Organization, 54(3), 385–399.

    Article  Google Scholar 

  • Greenhill, B., Ward, M. D., & Sacks, A. (2011). The separation plot: a new visual method for evaluating the fit of binary models. American Journal of Political Science, 55(4), 990–1002.

    Article  Google Scholar 

  • Guzman, A. (2008). How international law works. A rational choice theory. Oxford, UK: Oxford University Press.

  • Helfer, L. R. (2005). Exiting treaties. Virginia Law Review, 91, 1579–1648.

    Google Scholar 

  • Kaiser, K. (1978). The great nuclear debate: German-American disagreements. Foreign Policy, 30(1), 83–110.

    Article  Google Scholar 

  • Kleine, M. (2010). Making cooperation work: Informal governance in the EU and beyond. Paper delivered at the American Political Science Association Annual Meeting.

  • Koremenos, B. (2001). Loosening the ties that bind: a learning model of agreement flexibility. International Organization, 55(2), 289–325.

    Article  Google Scholar 

  • Koremenos, B. (2007). If only half of international agreements have dispute resolution provisions, which half needs explaining? Journal of Legal Studies, 36(1), 189–212.

    Article  Google Scholar 

  • Koremenos, B. (2012). An economic analysis of international rulemaking. Working Paper. Department of Political Science, University of Michigan, Ann Arbor.

  • Koremenos, B. (2013). Institutionalism and international law. In J. L. Dunnoff & M. A. Pollack (Eds.), International law and international relations: Synthesizing insights from interdisciplinary scholarship. New York: Cambridge University Press.

    Google Scholar 

  • Koremenos, B. (n.d.). The continent of international law. Journal of Conflict Resolution.

  • Koremenos, B. (book manuscript). The continent of international law. Ann Arbor, MI.

  • Koremenos, B., & Betz, T. (2013). The Design of Dispute Settlement Procedures in International Agreements. In J. L. Dunnoff & M. A. Pollack (Eds.), International law and international relations: Synthesizing insights from interdisciplinary scholarship. New York: Cambridge University Press.

    Google Scholar 

  • Koremenos, B., & Nau, A. (2010). Exit, no exit. Duke Journal of Comparative and International Law, 21(1), 81–119.

    Google Scholar 

  • Koremenos, B., Lipson, C., & Snidal, D. (2001). The rational design of international institutions. International Organization, 55(4), 761–799.

    Article  Google Scholar 

  • Leeds, B., Ritter, J., Mitchell, S. M. L., & Long, A. (2002). Alliance treaty obligations and provisions. International Interactions, 28(3), 237–260.

    Article  Google Scholar 

  • Lipson, C. (1991). Why are some international agreements informal? International Organization, 45(4), 495–538.

    Article  Google Scholar 

  • Mitchell, R.B. (2002–2011). International environmental agreements database project (Version 2010.3). Available at:

  • Nedal, D.K. (2011). Briefing 1—the US and Brazil’s Nuclear Program. June 9, 2011, available at

  • Norris, P. (2009). Democracy cross-national data, Release 3.0, Spring 2009. Available at Last accessed on October 11, 2012.

  • Oates, W. E. (1999). An essay on fiscal federalism. Journal of Economic Literature, 37(3), 1120–1149.

    Article  Google Scholar 

  • Oye, K. A. (1986). Explaining cooperation under anarchy: Hypotheses and strategies. In K. A. Oye (Ed.), Cooperation under anarchy (pp. 1–24). Princeton: Princeton University Press.

    Google Scholar 

  • Rosand, E. (2003). Security Council Resolution 1373, the Counter-Terrorism Committee, and the Fight Against Terrorism. The American Journal of International Law, 97(2), 333–341.

    Article  Google Scholar 

  • Schachter, O. (1977). The twilight existence of nonbinding international agreements. American Journal of International Law, 71(2), 296–304.

    Article  Google Scholar 

  • Simmons, B. A. (2009). Mobilizing for human rights. International law and domestic politics. Cambridge: Cambridge University Press.

    Book  Google Scholar 

  • Stone, R. W. (2011). Controlling institutions: International organizations and the global economy. New York: Cambridge University Press).

    Book  Google Scholar 

  • Szasz, P. (2002). The security council starts legislating. American Journal of International Law, 96(4), 901–905.

    Article  Google Scholar 

  • Tierney, M. J. (2008). Delegation success and policy failure: collective delegation and the search for Iraqi Weapons of mass destruction. Law and Contemporary Problems, 71, 283–331.

    Google Scholar 

  • Verdier, D. (2008). Multilateralism, bilateralism, and exclusion in the nuclear proliferation regime. International Organization, 62(3), 439–476.

    Article  Google Scholar 

Download references

Author information

Authors and Affiliations


Corresponding author

Correspondence to Barbara Koremenos.

Additional information

The research for this article was funded by National Science Foundation Grant, “The Continent of International Law: Theoretical Development, Data Collection, and Empirical Analysis” (SES-0801581), and National Science Foundation CAREER Award, “Designing International Agreements: Theoretical Development, Data Collection, and Empirical Analysis” (SES-0094376). I thank Timm Betz for his superb research assistance, my coders, and Ewan Compton, Alexis Juncaj, Logan Trombley, and especially Jennifer Herstein for case study research. Finally, Jeff Smith provided very helpful comments.

Electronic supplementary material

Below is the link to the electronic supplementary material.


(DOCX 57.7 kb)


(DTA 75.1 kb)


(DO 3.08 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Koremenos, B. What’s left out and why? Informal provisions in formal international law. Rev Int Organ 8, 137–162 (2013).

Download citation

  • Published:

  • Issue Date:

  • DOI:


JEL classification