We must find some better way. This will require a profound rethinking and reorganization of the way we conduct international relations. As things are now, international relations involve relations between states. How a state treats its own citizens involves relations within the state. The two relations are largely independent of each other because the states enjoy sovereignty over their territory and their inhabitants.
Sovereignty is an outdated concept but it prevails.
It derives from the time when kings wielded power over their subjects, but in the French Revolution when the people of France overthrew their king they assumed his sovereignty. That was the birth of the modern state. Since then, there has been a gradual recognition that states must also be subject to the rule of law but international law has been slow to develop and it does not have any teeth. We have the United Nations but the UN does not work well because it is an association of states and states are guided by their interests, not by universal principles, and we have the Declaration of Universal Human Rights. The principles which ought to govern the behavior of states towards their own citizens have been reasonably well-established.