Are Human Rights Universal?

If human rights are universal, then there has to be a universal justification for them — they have to be equally valid no matter which society you come from. What is this justification? John Locke, who is largely responsible for human rights talk, thought that they came from God. The writers of the American Constitution agreed with him. [It has been argued that we still accept universal human rights even though we have done away with the theological underpinning for them and have not found a replacement for it.]

Immanuel Kant thought that they come from reason, via the Categorical Imperative. It is common nowadays to claim that they come from the nature of a human being, though the details of how they so arise differ between many authors. Is it merely the concept of a human (or more commonly, a person) — and if so, which features of that concept? Is it our rationality (Kant), our special status granted by God (Locke), our immersion in community, our ability to empathize, our ability to have moral views, or something else?

If you believe that morality is relative — that what's right for me (or for us) may not be right for you, then it is difficult to see how you can support universal human rights at all. One account of rights is that they are granted by governments or rulers. If this is the case, then they differ from one society to another, and cannot then be universal.