Scholars and Tea Partyers gather to consider changing the Constitution

Calls to change the Constitution are suddenly everywhere, and they aren't limited to any political quarter. Rick Perry, the Texas governor and Republican presidential hopeful, has proposed repealing the 17th Amendment—the one permitting the direct election of U.S. senators—and some Tea Partyers have rallied around a proposal to let state legislatures overrule acts of Congress (the so-called Repeal Amendment).

At the same time, many on the left support a constitutional amendment, if necessary, to undo the Supreme Court's 2010 Citizens United opinion, which grants corporations many of the same free-speech (and campaign-donation) rights that ordinary citizens have.

Lawrence Lessig, the Harvard law professor best known for his work on intellectual property but more recently a good-government reformer, has sensed the ferment and seized the moment: This month he will play host, with Mark Meckler, a national coordinator of the Tea Party Patriots, to a conference in Cambridge to discuss whether the time has come for a constitutional convention. Calling such a convention is a right given to Congress and the states under Article V of the Constitution but has never been exercised.

"Fifteen years ago, I didn't have the sense that the republic was prepared for this," Mr. Lessig says. "Now I do."...