From Existential Comics:
Social Contract Theory is the area of philosophy that deals with how an individual deals with the society that they belong to. In modern philosophy, it is mostly closely associated with Thomas Hobbes, John Locke, and Jean-Jacques Rousseau. Hobbes, in particular, thought that humans were naturally in an "all against all" violent state before civilization, and in order to avoid this, individuals cede authority to a sovereign. Rousseau argued for a more democratic society (although Hobbes was neccesarily arguing against democracy, but merely for a unified society), where instead of a single sovereign, we cede our rights to the will of the majority. He attempted to reconcile individual freedom with this sort of ceding of rights to the majority, or to a society as a whole. For Rousseau, in some sense, in order to fully become free we had to give up some of our freedom, because a society which individuals did not give up freedom would be less free. Although not an example Rousseau gives, we can see that a society where individuals give up the right to own slaves becomes more free, on the whole. If we do not form some kind of social contract, then it becomes very difficult to guarantee any kind of legitimate freedom for anyone, because anyone's freedom could be taken away by arbitrary force.
Camus, while he didn't explicitly talk about social contract theory, was something of an anarchist, and wrote in The Rebel that an individual must always have the right to rebel against an unjust society.