In Congress, a move to end health insurers’ exemption from federal anti-trust laws is gathering steam. Insurers have squawked that the effort is a political ploy. In mid-October, a dubious report from the industry linked a Senate health-reform bill to dramatically higher premiums. Shortly afterward, Sen. Patrick Leahy (D.-Vt.) convened a Judiciary Committee hearing on scrapping the anti-trust exemption, and President Obama approved exploring the idea. On Oct. 21, the House Judiciary Committee voted to do away with the exemption. Senate Majority Leader Harry Reid (D.-Nev.) signaled his hopes to follow suit. We would be surprised if politics did not figure in this fight. Even so, three Republicans joined the House vote to repeal the exemption.

The anti-trust exemption is a historical artifact that, by dampening competition, may well be adding to health-care costs in at least some parts of the country. The power to regulate insurers has traditionally belonged to the states, and was fortified by the unfortunate McCarran-Ferguson Act of 1945. Congress approved the measure in response to a Supreme Court decision that found the insurance industry to be part of interstate commerce, and hence subject to federal anti-trust laws. McCarran-Ferguson protects health insurers from being prosecuted for price fixing, bid rigging and market allocation.

In many states, one or two companies dominate the health-insurance market. They have little incentive to compete on price. Further, dissatisfied customers in one state may not buy a policy in another. We noticed the other week, for instance, that an insurance policy in Maryland has a premium half the size, and with better coverage, than a similar policy sold by Blue Cross and Blue Shield of Rhode Island, but other than by moving to Maryland there is no way to buy it.

At the Senate hearing, Christine Varney, the head of anti-trust enforcement at the Justice Department, testified for ending the exemption. Nearly all the states’ attorney generals are on her side, suggesting that at the very least, they smell smoke.

There is some danger that anti-trust actions, by breaking up markets, might in some places reduce health insurers’ bargaining power, making it harder for them to hold down prices. But for the past few years, federal anti-trust activity has been anemic, at best. A sudden, dramatic ramping up seems unlikely. Meanwhile, insurance companies have shown a remarkable ability to take advantage of what are in some states semi-monopolies that have avoided the inconveniences of competition. A few well-aimed anti-trust actions are more likely to benefit than harm consumers.

Getting rid of the antitrust exemption and letting people shop for insurance nationally would be good steps in controlling costs.