The modern law of treaties applies regardless of whether a treaty is publicized. The secrecy of an international agreement does not affect its legal force, nonpublicized agreements may be used in interpreting a publicized treaty, and mere failure to comply with domestic requirements concerning publicity does not invalidate the treaty or a state's consent to be bound by it. Under the UN Charter, UN members may not invoke an unregistered treaty or international agreement before a UN organ, but the rules on state responsibility are not concerned with the secrecy or publicity of primary obligations. Injured states may resort to countermeasures for breaches of secret treaty obligations and can suspend compliance with secret treaty obligations as a countermeasure against the responsible state. States may also seek to enforce obligations in secret treaties by bringing claims in international courts and tribunals outside the UN system—and these courts and tribunals have proliferated.

Megan Donaldson's The Survival of the Secret Treaty: Publicity, Secrecy, and Legality in the International Order recounts the ways in which lawyers played an important but complicated role in governmental decisions about whether and when to register secret agreements. On the one hand, these lawyers urged their governments to comply with the League of Nations and UN Charter registration processes. On the other hand, these same lawyers used their drafting and interpretive skills to enable their governments to employ secrecy where necessary, while helping their clients minimize the fact and size of any legal violations that occurred. They thus urged legal compliance on the front end and reduced the extent of noncompliance on the back end.