In this paper I argue that there is objectivity in international human rights law, against which the justifiability of arguments can be determined, and which could advance the universality versus relativity of human rights debate. Revisiting the three schools of treaty interpretation and applying the three elements of Radbruch’s rule of law, I discuss how the interpreter’s job of balancing those schools has limited room for manoeuvre. I further propose an approach to help jurists detect unjustifiable arguments in treaty interpretation, (...) often in the disguise of relativism. That approach consists of: a non-justifiable argument contradicts all three schools of treaty interpretation; or ignores all three; a justifiable argument is supported by at least one of these schools; a better argument is a more balanced argument, i.e. supported by more elements of interpretation. Finally, I argue that there is a degree of objectivity in each school of treaty interpretation, which is supported by shared intention and speech act theory, and can therefore be held to apply to the whole process of treaty interpretation. I illustrate above arguments with a case, a doctrine, and a country. (shrink)