All told, more than 10,000 constitutional amendments have been introduced in Congress since 1789. If some of the choicer ones had been accepted, the U.S. would boast a President selected by lot from among the members of the Senate, and a Supreme Court whose members could be removed by popular vote. But only 33 proposals have won the necessary approval from two-thirds of both houses of Congress. And just 26 have passed the final hurdle of adoption by legislatures in three-quarters of the states. The last of them, lowering the voting age to 18, turns 18 itself in two years.
That...