For something to be due to someone there must first exist a right to that thing. Ah, I thought at this point, contrary to what my boss may think, when he pays me my salary at the end of every month, he is not doing me a favour. He is merely being just in paying me that which by right is mine. A salary which I have earned with my work. Of course, my employer in paying me a salary, also has the right to demand that I work for that salary.
Justice thus presupposes right.
If I did not have a previous agreement with my boss to receive a certain sum of money in return for a concrete service, there would be no basis to bring justice into play on the issue. But not all rights are the result of one's work or the consequence of man's action. While some rights are the result of common agreement or convention, there are other rights which are more deeply founded in nature itself, in that which is usually referred to as natural law. Natural law bears more weight than human convention. Driving on the right, for instance, is a human convention and could be changed at any time.