The concepts of estoppel and acquiescence are difficult to disentangle from other related concepts, such as recognition, admissions and recourse to subsequent conduct in the interpretation of a treaty. As one noted authority states when analysing the relevance of these concepts to the judicial determination of territorial disputes: ‘Recognition, acquiescence, admissions constituting a part of the evidence of sovereignty, and estoppel form an interrelated subject-matter, and it is far from easy to establish the points of distinction.’ Referring more particularly to the concept of estoppel, the same authority argues:

Practitioners in international law, particularly those who have been involved as counsel in long-standing territorial disputes, are aware that arguments founded on notions of estoppel and acquiescence figure prominently in the armoury of weapons at their disposal.