When somebody else pays for their drinks, most partygoers find they want and need more than a modest amount to drink because at an open bar, the cost of a drink is the time spent waiting in line for service. At a cash bar, lines are shorter because most people find they just don’t need that much to drink when they have to pay for it.

What holds for drinks also holds for crop insurance. Since 2001, taxpayers have paid more than two-thirds of the tab for farmers’ crop insurance purchases. Almost all of this federal largess goes to producers of corn, soybeans, wheat and cotton, with the largest subsidies filling the pockets of the largest and wealthiest farmers. Advocates for continuing these subsidies claim that the fact that farmers buy large amounts of the most expensive and heavily subsidized crop insurance product is proof of the importance of the program. But using farmers’ current crop insurance decisions to measure how much they value insurance is as valid as measuring the value of drinks by how much alcohol is consumed at an open bar.

Crop insurance subsidies were dramatically increased in 2000. Since then, farmers have increased the amount of insurance they buy and have overwhelmingly chosen to insure their crops with Revenue Protection. This is the champagne of crop insurance products. It protects against revenue shortfalls when crop prices decline and against yield shortfalls when crop prices increase. Revenue Protection can cost up to 80 percent more than regular revenue insurance that only protects against revenue shortfalls. Most of this 80 percent extra cost is paid for by the taxpayer. The record $12.7 billion insurance payout to corn and soybean farmers in 2012 was more than twice what they would have been had subsidies not induced farmers to buy Revenue Protection rather than regular revenue insurance.

Sen. Jeff Flake, R-Ariz., and Rep. John J. Duncan Jr., R-Tenn., recently introduced legislation that would sharply reduce the powerful incentive farmers have to increase their consumption of crop insurance. The extent to which farmers’ purchases of insurance would change under the Flake-Duncan proposal is reflected by the $40 billion in tax dollars that the Congressional Budget Office estimates would be saved over 10 years. Tellingly, the bill would not restrict farmer choice over the type of crop insurance they could buy or eliminate subsidies. It would only reduce the taxpayer portion of the tab.

Just as charging for drinks dramatically reduces alcohol consumption, increasing the farmers’ share of the cost of managing their risk would dramatically reduce their use of insurance. This policy change would dramatically lower taxpayer costs while simultaneously improving agricultural efficiency. Rather than taxpayers taking the risk out of crop production, which in fact encourages farmers to adopt more risky business and production strategies, changing the program would allow those farmers who can best manage their production and price risk to reap the highest rewards. Returns would flow more to good farmers rather than just to any farmer who uses taxpayer dollars to buy the most insurance.

Perhaps we are entering an era in which Congress will need to be more accountable for the subsidies it provides to farmers and other industries. If so, then Congress and the administration should seek to spend money on programs only where there is a clear public interest at stake and even then only on programs where that clear public interest is being met in a cost-effective manner. The crop insurance program fails both tests.

In an attempt to rationalize the program’s $9 billion annual average cost, its supporters argue that this is a small price to pay for stability in our food supply. But the idea that the U.S. food supply depends on a taxpayer-provided “safety net” is ludicrous. The United States produces large surpluses of food for the export market, and farming has never been as profitable as it is now. Simply put, the only public interest at stake in the farm subsidy debate is the increase in interest on the national debt.

It may be too much to expect Congress to actually eliminate subsidies to a program that serves no broad public purpose, but perhaps it is not too much to ask for greater cost-effectiveness. A simple first step would be to ask farmers to pay a greater share of the cost of insuring their crops. Just as conversion of open bars to cash bars reduces excessive consumption of alcohol, this step would dramatically reduce farmers’ over-consumption of insurance.

Bruce Babcock is a professor of economics at Iowa State University and a contributor to the American Enterprise Institute’s American Boondoggle Project.