Ethical Relativism

“Ethical relativism is the theory that holds that morality is relative to the norms of one's culture. That is, whether an action is right or wrong depends on the moral norms of the society in which it is practiced. The same action may be morally right in one society but be morally wrong in another. For the ethical relativist, there are no universal moral standards -- standards that can be universally applied to all peoples at all times. The only moral standards against which a society's practices can be judged are its own. If ethical relativism is correct, there can be no common framework for resolving moral disputes or for reaching agreement on ethical matters among members of different societies.”   (Velasquez, June, 1992)
You cannot judge another’s ethics according to your own.   They are going to be very different and because there are not universal moral standards, it is going to be very difficult to apply your ethics against any other person.
I do not believe that there are not ways to resolve cultural disputes or reaching agreements on ethical matters when different societies are involved.   We do it all the time.   There is give and take on both sides.   Even though ethics may be different, there are always ways to come to an agreement with compromise on both sides.   With both sides compromising there is always a way to find common ground and make things work for both sides.

Velasquez, M. A. (June, 1992). Ethial Relativism. Issues in Ethics, Santa Clara University, The Jesuit University in Silicon Valley.