For example; on an island people kill their babies as they are born, if the population on the island is on the verge of going higher than what they know the food sources can support. If the majority of people on the island agree to accept this practice it becomes a custom. It moves from being a custom when the majority defines it as a good behavior based on their belief of how they should behave, meaning moving away from being done just out of necessity for survival in relation to the food sources. An islander who kills a newborn child for any reason thus exerts a right.
If the islanders create a rule system to live by they have given authority to that system. The system acts as an automaton functioning in what manner the islanders agreed upon. Obviously a system must be run by some islanders, an automaton cannot fulfill actions without some force that can effect its mandates. However the automaton is authority, the islanders to effect its mandates are only functionaries. Authority is only that which the islanders define it to be. The functionaries are simply facilitators of authority, they are not authority, nor do they make authority.
The point in the above example is that rights are defined by the islanders who apparently have no allegiance or belief in anything above themselves. They have defined good and bad behavior. Thus they are the definer and giver of rights.