One item on voters’ short list for congressional action is addressing the growing problem of surprise medical bills.

Insured patients should be confident that if they receive care at a facility that is in their health plan’s network or have a medical emergency, they will be responsible only for their share of the plan’s negotiated rates.

But all too often, a patient receives a bill afterward from an anesthesiologist, for example, that wasn’t “in network.” The insurer says the charge isn’t its responsibility, and the patient is on the hook—often for thousands or tens of thousands of dollars.