Cass Yuan: i think you have to enrol with me (joke lang pare)!
anyway, jus gogens goes hand in hand with obligation erga omnes...meaning in latin "towards all" or towards everyone". In public international law, it has been used as a legal term describing obligations owed by states towards the community of states as a whole. An erga omnes obligation exists because of the universal and undeniable interest in the perpetuation of critical rights (and the prevention of their breach). Consequently, any state has the right to complain of a breach. Examples of erga omnes norms include piracy, genocide, slavery, torture, and racial discrimination. The concept was recognized in the International Court of Justice's decision in the Barcelona Traction case [(Belgium v Spain) (Second Phase) ICJ Rep 1970 3 at paragraph 33] which states:
"… an essential distinction should be drawn between the obligations of a State towards the international community as a whole, and those arising vis-à-vis another State in the field of diplomatic protection. By their very nature, the former are the concern of all States. In view of the importance of the rights involved, all States can be held to have a legal interest in their protection; they are obligations erga omnes. [at 34] Such obligations derive, for example, in contemporary international law, from the outlawing of acts of aggression, and of genocide, as also from the principles and rules concerning the basic rights of the human person, including protection from slavery and racial discrimination. Some of the corresponding rights of protection have entered into the body of general international law . . . others are conferred by international instruments of a universal or quasi-universal character.
Now based on the above opinion by the ICJ, in the Barcelona Traction Case (I remember my good friend, Harry Roque, for that is one of his favorite case), since torture is outlawed or detested by the international community, the international protocols against torture, should be observed in good faith by the signatory and non-signatory states.
All I can say, is that in the matter of outlawing torture, jus cogens and pacta sunt servanda compliments each other, rather than a legal limitation.