The X-Men are the best super-mutant fighting force the world has ever seen. It's obvious Professor Xavier knows what he's doing, at least most of the time.
If Professor X has any sense (which he clearly does), he probably has his mutant students sign some kind of contract before they officially join the X-Men. It would be the prudent thing to do. I'm sure there are all sorts of X-rules, X-non-disclosure agreements, and X-pectations that would be necessary in order to nurture a proper team environment and, of course, go save the world on occasion. Once an individual has signed the X-contract, that X-Man is expected to abide by the rules he agreed to. It would certainly be reasonable for the X-Men to develop their own way of resolving internal disputes without any outside interference. Such is the wonder of private contracts.
Now let's talk about another contract, namely the "Social Contract". Proponents of state power use the Social Contract to explain the legitimacy of the state's authority over the people. Supposedly we are all signatories to the Social Contract wherein we give up some of our rights in exchange for security that lets us exercise the rest of our rights. Everything from taxes, surveillance, gun control, censorship, and Obamacare are theoretically derived from the Social Contract, which we allegedly agreed to. Whether we vote for or against any law, or don't vote at all, we all purportedly give our consent to the laws of the land. So says the Social Contract.
One of these examples of a contract is logical, can be explained clearly, and has precisely defined clauses; and the other example is completely imaginary.
Contracts work on an individual level because everything is aboveboard. Everything is spelled out nice and neatly. I admit that certain contracts try to make things tricky with clever wording but theoretically everything can be properly interpreted with a lawyer. Now contrast that with the Social Contract. Proponents of the Social Contract would have us believe in some great invisible document with all our names on it somewhere in the void, all meant to govern society as a whole, with no discernible way to peruse the exact contents. It sort of sounds like a religious belief. I'm all about religion, but not when it forces others, at gunpoint if necessary, to do something that they would rather not.
The Social Contract is a poor attempt to legitimize the improper use of force by government. The only real "Social Contract" is simply mutual respect for others and their property. Such mutual respect and clearly defined property rights serve as a basis for resolving any conflicts without any interference from the state.