There are many reasons Americans pay more for health care than citizens of any other country. But one of the most powerful forces driving cost increases is buried in a little-known set of regulations concerning emergency room care.

These regulations have granted hospitals what is essentially a monopoly over emergency room patients, allowing them to charge basically whatever they want.

Readily available emergency treatment is among the most fundamental services of our health care system. To ensure it, most states require health care plans to tell their members to go to the nearest hospital in an emergency and that insurance will cover the visit — even if their plan does not have a contract with that hospital and the emergency care they receive will be out of network. This provision is meant to assure timely access to needed care and, although some patients have to wait hours to be seen by a doctor, and some still get hit with additional charges, it generally works pretty well.

The problem is that the rules give hospitals tremendous pricing power when they’re negotiating with health insurance companies. Increasingly, hospitals have learned that if they demand higher prices from health plans and do not get them, the hospitals can just cancel their contract. They will still get paid for treating emergency patients under those plans — and in fact will be paid more, because those patients will be out of network. (While this applies only to emergency room patients, about half of all hospital admissions come through emergency rooms.)