Pacta sunt servanda versus flexibility in the suspension and termination of treaties

Pacta sunt servanda – the rule that treaties are binding on the parties and must be performed in good faith – is universally accepted as the ‘basis of all treaty law’. Still, fundamental as it may be, it is neither unqualified nor completely isolated from other considerations. Treaties are the principal means that States and/or other subjects of international law use to formalize their mutual commitments. It would defeat the very purpose of their conclusion if they were not resistant to subsequent developments, or if the commitments undertaken therein could be easily retracted by one party. On the other hand, if no room is left to accommodate change, a treaty may lose its foundation on the agreement of the parties, or its object and purpose may be frustrated over time, turning its provisions into a dead letter. More pragmatically, the negotiating parties would more likely be reluctant to enter into an agreement that binds them unconditionally in perpetuity. The tension between stability and change underlies international law in its entirety and, particularly, the law of treaties. It is exemplified in the pacta sunt servanda rule’s juxtaposition to grounds for invoking unilaterally the suspension or termination of the pactum, as is, for example, the clausula rebus sic stantibus.