In 301 AD, the Roman emperor Diocletian imposed price controls on most commodities and professions in the empire. The penalty for raising prices was death. Yet the controls failed utterly, leading to shortages, more inflation and the near collapse of the imperial economy. Now, nearly two millennia later, President Obama seems determined to demonstrate how little we've learned. Yesterday, the president proposed giving the federal government the power to regulate insurance premiums. Undoubtedly, this will be politically popular -- at least, in the short term. Insurance companies aren't exactly America's most loveable industry. Recent premium hikes will result in real...