The Obama administration has made a number of important proposals designed to limit the availability of assault weapons and to prevent felons, those with serious mental illness and minors from purchasing guns of any kind. There is another complementary approach that should be tried, especially because significant parts can be accomplished at the state level: Raise the price of gun violence. Here are some ways to do that, without taking away anyone’s firearms.

First, use the tax system to raise the price of violence. Heavily taxing the purchase of firearms would probably never pass, and would do nothing about the millions of guns already in private hands. Besides, guns don’t kill — bullets do, and they have to be purchased for guns already owned. Many gun owners use their weapons for hunting or target practice, and there is no reason to tax those ordinary uses. The trick is to find a way to impose significant taxes on those who buy bullets for illegitimate uses. That means distinguishing between legitimate and illegal uses of bullets.