Here we go again: Republican politicians are rolling out an easily digested sound bite: Allowing health insurers to sell coverage across state lines would solve the problem of high premiums. In the current presidential race, Donald Trump, Sen. Marco Rubio (R-Fla.), Sen. Ted Cruz (R-Texas), Sen. Rand Paul (R-Ky.), Rick Santorum, Gov. Bobby Jindal (R-La.), and the recently departed Gov. Scott Walker (R-Wis.) all proposed it. It has been a feature of Congressional Republican proposals since at least 2010.

The only problem is that such a reform has no effect. Back in 2010, Georgia sacrificed its sovereignty to regulate health insurance, but premiums didn’t change. The reason is that if a health plan wants to offer coverage in a state, it already can easily do so. Health insurers enter and exit markets all the time. Aetna and Cigna are domiciled in Connecticut, but that does not prevent them from offering plans in other states. Insurance commissioners do not discriminate between in-state and out-of-state insurers when they issue insurance licenses.