I'll be an international relations graduate from Turkey (though I still have 2 years =) ) and I want to be an arbitrator. So I'm thinking about mastering on dispute resolution or arbitration. but is it possible to be admitted such programmes in USA or UK?

What possible difficulties may I face in admission? What exams am I supposed to pass generally other than TOEFL? Should I take GRE or LSAT or both?

and what kind of preparations should I do, what is your advices?
I guess I'M in the beginning of the road. I hope I'M not too late for any preparations ._.

Thanks for attentions ^^