In 2005, Matthew Craven noted that “[t]he phenomenon of unequal treaties [has] largely evaporated as an issue from the domain of international law”. In Craven's opinion, international lawyers have demonstrated an “unwillingness to engage effectively with the problem of equality”. This paper argues that states have, in fact, addressed issues of inequity in recent treaty negotiations. When states have had to unite around common goals, various methods of according special and differential treatment have been used to address concerns about substantive equality. Drawing upon precedents from environmental law and international trade, this paper proposes the recognition of a principle of equality in treaty relations. It is suggested that the persistence of inequality should provide grounds for seeking the renegotiation of a treaty, and that a general principle in favour of remedying unacceptable levels of inequality should be applied to build flexibility and stability into treaty relationships.