Imagine two written constitutions. One sets out a standard series of political structures and governmental empowerments and limitations; it concludes with a clause saying: “Anything in this constitution can be changed by the passage of ordinary legislation as spelled out in this constitution.” Were this “parliamentary sovereignty” model – found, for example, in the Austrian Constitution – present in the United States Constitution, then constitutional amendments could come about by agreement of majorities in both houses of Congress and assent by the president or by two-thirds vote in each house overriding a presidential veto. Our second constitution comes to a radically different conclusion: “And the Articles of this confederation shall be inviolably observed by every state …; nor shall any alteration at any time hereafter be made in any of them; unless such alteration be agreed to in a congress of the united states, and be afterwards confirmed by the legislatures of every state.” Not only does the second constitution require assent by a different institutional layer from that of the national political assembly, in this case, the constituent states of the union; it also requires that this latter act of assent be unanimous. By definition, as with Poland's (in)famous liberum veto, this allows one holdout state to countermand the desire of every other state (and, presumably, the national legislature) for constitutional change. Both of these examples are taken from real political life, even though the latter constitution, the U.S. Articles of Confederation, lasted only six years.