State A and State B, two sovereign states, enter into a 10-year mutual defense treaty. After five years, State A finds that the more progressive State B did not go to the aid of State A when it was threatened by its strong neighbor State C. State B reasoned that it had to be prudent and deliberate in reacting to State C because of their existing trade treaties.
(a) May State A now unilaterally withdraw from its mutual defense treaty with State B? Explain your answer. (2.5%)
(b) What is the difference between the principles of pacta sunt servanda and rebus sic stantibus in international law? (2.5%)
(c) Are the principles of pacta sunt servanda and rebus sic stantibus relevant in the treaty relations between State A and State B? What about in the treaty relations between State B and State C? Explain your answer. (2.5%)
(a) No. Answer
Under the 1969 Vienna Convention on the Law of Treaties, a material breach of a bilateral treaty by one of the parties entitles the other to invoke the breach as a ground for terminating the treaty or suspending its operation in whole or in part. Rule
In the case at bar, State C only made threats against State A. No international armed conflict began that could trigger the mutual defense treaty compelling State B to defend State A against State C. Accordingly, State B did not commit material breach. Apply
Thus, State A may not unilaterally withdraw from the mutual defense treaty. Conclusion
(b) Under international law, pact sunt servanda means every treaty in force is binding upon the parties to it and must be performed by them in good faith. On the other hand, rebus sic stantibus provides that a fundamental change of circumstances which has occurred with regard to those existing at the time of the conclusion of a treaty, and which was not foreseen by the parties may be invoked to terminate or withdraw from a treaty, subject to exceptions.
(c) For the treaty of A and B, the principle of pacta sunt servanda is applicable between State A and B as they have a mutual defense treay. State B cannot invoke the principle of rebus sic stantibus as there has been no fundamental change of circumstances between State A and State B, nor State B and State C. Rather, State B was merely being prudent with its trade relation with State C.
For the treaty of B and C, the principle of pacta sunt servanda is applicable between State B and C as they have an existing trade relation. Neither State B nor State C can invoke the principle of rebus sic stantibus as there has been no fundamental change of circumstances between them. While there may have been a threat made by State C against State A, no overt act or actual harm has been committed that could trigger the mutual defense treaty and thus compel State B to defend State A in turn resulting in a direct conflict with State C.