AMERICA’S IMMIGRATION DEBATE is fraught with demagoguery and suspect analogies. Witness Rep. James Sensenbrenner’s recent description of employers who exploit illegal immigrant labor as “21st-century slave masters.”

Besides that whopper, few rhetorical tropes are as inane as the suggestion that a U.S.-made security fence along the Mexican border would be no different than the Berlin Wall, which separated (Free) West Berlin from (Communist) East Berlin. The Cold War parallel, a favorite of Mexican politicians and activists, is frequently trumpeted by Democrats, such as Sen. Ted Kennedy and Rep. Sheila Jackson Lee. But even the Wall Street Journal editorial page, the most consistent voice of the open-borders right, trotted it out shortly after President Bush unveiled his guest-worker program in January 2004. “We could always . . . build a Berlin Wall along the 2,000 miles of U.S.-Mexican border,” the Journal mused, “but we doubt Americans would be morally comfortable with [that].”