Emergency medical care is an exception to the general principle of market exchange, whereby services are voluntarily bought and sold, with sellers competing on price. Under federal law, hospitals are required to treat patients that arrive needing emergency medical treatment, regardless of their ability to pay—but allowed to subsequently charge whatever they wish. In recent years, medical providers have increasingly exploited this arrangement by threatening exorbitant charges for out-of-network emergency care in order to force insurers to agree to generous reimbursement terms across the board. Patients have frequently been caught in the crossfire and forced to pay large “surprise bills” for emergency care by hospitals or doctors who remain out of network.