NATO was built to counteract the Soviet Union in its day and time. At this point there is no threat coming from the Soviet Union, because there is no Soviet Union anymore. And where there was the Soviet Union once, there is now a number of countries, among them the new and democratic Russia.
In the case of Yugoslavia v. NATO, one of the charges was genocide. The U.S. appealed to the court, saying that, by law, the United States is immune to the charge of genocide, self-immunized, and the court accepted that, so the case proceeded against the other NATO powers, but not against the United States.