Second, because domestic politics is increasingly insufficient to address important areas of public policy alone, international law's principal function is to serve as a mechanism by which the domestic politics of different states can be linked, in order to construct a formal mechanism of international politics. Within domestic politics, this international political linkage allows for the formation of domestic political coalitions that could not be formed in autarky. International law is thus a mechanism by which the costs or benefits to other states can be brought to bear on national decision making