Pacta Sunt Servanda，条约必须遵守原则，是国际法基本原则，为《维也纳条约法公约》序言及第26条所明确规定。指的是条约缔结后，各方必须按照条约的规定，行使自己的权利履行自己的义务，不得违反。

在签订或加入国际条约的时候，对国内法律进行相应调整；在国内法律制定过程中，主动对照国际条约；在国内法律被认定违反国际条约之后，对该法律进行相应修改。

参考双语例句：

First, Pacta Sunt Servanda principle is the leading principle of solving territorial disputes; international treaty is the overriding criterion of solving territorial disputes. 

首先，条约必须遵守原则是解决领土争端必须遵守的首要原则，国际条约是解决国际领土争端的首要依据。

He has written and published extensively on the law of the United Nations Charter; international courts and tribunals; alternatives to treaty making; the assertion of jurisdiction by the Court; the law of the sea; outer space law; the law applicable to Antarctica; the principle of self-determination in international law; international humanitarian law; international law and multiculturalism; solidarity as an emerging principle of international law; humanitarian intervention; the binding nature of the decisions of the Court; the Court’s Rules and Practice Directions; the principle of pacta sunt servanda in the Court’s jurisprudence; and provisional measures in disputes between African States before the Court.

他发表和出版了大量关于以下内容的著作：《联合国宪章》；国际法院和法庭；订立条约的替代方法；法院申明管辖权；海洋法；外层空间法；适用于南极的法律；国际法中的自决原则；国际人道主义法；国际法和多元文化；作为国际法新生原则的团结；人道主义干预；法院判决的约束性质；法院命令和程序指示；法院判例的条约必须遵守原则；以及法院处理非洲国家之间争端的临时措施。

It is in fact the principle pacta sunt servanda itself which would be called into question, in that at any moment a party to a treaty could, by formulating a reservation, call its treaty obligations into question; in addition, this would excessively complicate the task of the depositary.

这实际上是 pact sunt servanda( 条约必须遵守) 的原则本身会出现问题，因为任一缔约方在任何时候都可以通过提具保留的办法对其条约义务提出疑问；此外，这样做会使得保存人的任务过分复杂化。