Bernie Sanders this month unveiled a $2.5 trillion housing agenda, but the price tag isn’t the only shocker. “Under my plan,” he told union members in Las Vegas, “we will establish a national rent-control standard, capping annual rent increases throughout the country at no more than 1½ times the rate of inflation or 3%, whichever is higher.”

Oy. Economists of all stripes agree rent control doesn’t work. A mere 2% think it has positive effects, according to a 2012 survey by the IGM Forum. In other contexts Bernie might cite...