I hate talk of "rights" because it is so often void of content. Rights do not exist except as the result of duties, both of which exits only within the context of relationships, which are in turn governed by justice. If you do not speak about "rights" in connection with these other three things, then you are not speaking about anything at all.
A right is, by definition, something which a person is due from some other person, people or entity. If you are due something from someone, then they--again, by definition--have a duty to render to you that which you are due. So rights do not exist except where duties exist and vice versa. One cannot exist without the other.
And neither can exist except within a relationship, since their very existence demands that a relationship exists. A relationship is, at its simplest, a reference to another. If I have a duty, it references the one I have the duty to by definition. The same is true with a right. The nature of the relationship that exists depends upon how the relationship came into existence and who the relationship is between. The relationship's nature governs what rights and duties are present within it.
Justice is the virtue of rendering to each what they are due. Someone is due something because he has a right to it and another has a duty to provide it for him. These rights and duties exist within the relationship and depend upon its nature. Thus justice rules what rights and duties exist within what relationships.
As such, rights are not the starting point in a discussion of ethics and politics. The starting point is what type of relationship exists and what justice says about it. For it is only from these that rights and duties can be derived.