The original corn laws put tariffs on imported grain in an effort to help domestic producers. That was nearly two centuries ago, in England, and the experiment is taught as an example of bad economic policy. But people never learn and in this country, today, we have the renewable fuel mandates which have been a boon to corn farmers in Iowa (among other states) where presidential candidates are obliged to speak in favor of a policy that is a drag just about everywhere else in the country. The ill effects include higher gas prices, poor engine performance in automobiles, and damage to smaller engines found in chain saws, leaf blowers, and lawn mowers.

So, as Amy Harder at the Wall Street Journal writes,