The two dimensions of federalism can be distinguished by references to "vertical federalism," involving the troublesome nation-state power relationships, and "horizontal federalism," involving the sometimes adversarial relations among the states. The Supreme Court has moved the division of powers both along the vertical continuum between national supremacy and dual federalism as well as along the horizontal continuum between partiality and parity. Vertical federalism has experienced swings between domination by the federal government—confirming Professor Stone's view—and a modicum of independence for the states, possibly providing the valuable attributes that keep the states as viable units. In vertical federalism, power conflicts arise between the federal and state jurisdictions when under their respective powers the Congress, the president, or the Supreme Court attempt to impose their will on the states. The horizontal federalism continually confronts the Supreme C.