The principle of free consent means that a State cannot be bound by a treaty to which it has not consented (article 34 VCLT).
Pacta sunt servanda (agreements must be kept) is embodied in article 26 VCLT: ‘Every treaty in force is binding upon the parties to it and must be performed by them in good faith‘. Likewise, the concerning treaty does not affect on a third party.- The maxim pacta tertiis nec nocent nec prosunt: article 34 VCLT. Exceptions:
International customary law.
If the treaty confers a right to a third party and consent its application.
The principle of good faith (applicable during all the life of a treaty, from its negotiation, through its performance and up to its termination).