That idea is a centerpiece of several alternative reform proposals. It would indeed lower insurance premiums for some people, namely the young and healthy who already have a relatively easy time finding affordable coverage. But it would raise costs for those who are having the toughest time under the current system—the sick and the aging.

Here’s how it would work. Anyone in the market for an individual policy could shop for coverage anywhere in the country. (If you’re on Medicare or get your coverage through a job, none of this would apply to you.) Right now, you can only buy an individual policy that’s approved for sale in the state where you live. And states vary widely in how strictly they regulate insurance. A few states require insurers to accept all comers, young and old, sick and well. In other states, insurers can turn down whoever they want, or charge older people or those in less-than-perfect health higher premiums. Some states have relatively strict rules about what health insurance has to cover, while others allow the sale of plans with very skimpy benefits.

Not surprisingly, the more consumer protections a state has, the more expensive health insurance tends to be. That’s because insurers have to collect premiums high enough to cover people in less-than-ideal health, and pay the cost of more of their care.

So what would happen if you could buy insurance in another state?