Want to see what's wrong with the newly enacted energy bill? Just take a look at your toilet.

If it's a low-flush toilet, that is. These water-stingy models were mandated under the 1992 Energy Policy Act. After the provisions took effect in 1994, millions of Americans remodeling their bathrooms came in for an unpleasant surprise. Many of the new water-saving toilets cost more and performed worse than the ones they replaced. Homeowners complained that they had to flush more than once, which, in addition to being annoying, cut into the water conservation purpose behind the law. It took many years before the bugs were worked out of the new toilets, and there are still plenty of unhappy flushers out there.

Or look at your grocery bill. Thanks to the 2005 energy law, agricultural-based renewable fuels, mostly ethanol derived from corn, must be mixed into the gasoline supply. The mandate has raised the cost of driving, since ethanol-containing blends have lower fuel economy. Worse, the diversion of significant amounts of corn to ethanol production has led to a near-doubling of corn prices, in turn leading to higher prices for food items such as corn-fed meat and dairy products. An Iowa State University study estimates that the ethanol provisions have raised food prices by $47 annually per capita.

The latest energy bill continues in this tradition by being filled with provisions likely to backfire in the years ahead. Though it mercifully left toilets alone, the law does have convoluted efficiency requirements impacting light bulbs, boilers, refrigerators, dishwashers, clothes washers and air conditioners. It's only a matter of time before one or more of these provisions lead to new consumer headaches.

Worst of all, the new law includes a five-fold increase in the amount of ethanol that must be added to the gasoline supply, from 7.5 billion gallons per year to 36 billion. The current mandate is bad enough, but the new one could set records for pain at the pump and at the supermarket.

There shouldn't be any mystery why these laws fail. They all involve Congress trying to force the public into using something the marketplace has rejected. If newfangled toilets or increased ethanol usage actually made sense, they would catch on without heavy-handed government mandates. Ditto the required modifications to appliances.

More often than not, this kind of government interference with the free market works to the detriment of consumers. Washington may think it is passing energy bills, but all it's really doing is proving the law of unintended consequences.

Ben Lieberman is a senior policy analyst in the Roe Institute for Economic Policy Studies at The Heritage Foundation.