Now Attorney General Eric Holder says never mind all that, and Americans should mellow out about such legal nuances. Justice’s four-page memo is dressed up in the language of enforcement priorities and “limited resources,” but as a practical matter it means no prosecutor who cares about his career—which is to say all of them—will bring another marijuana case.

Justice warns that it will intervene if it discovers that marijuana is flowing to children or being trafficked to states where it is still illegal, though under federal law it is still illegal in all states. The memo tells prosecutors to ignore even “large-scale, for-profit enterprises,” which are usually targets for taxation.

Prosecutorial resources aren’t unlimited, and some crimes deserve more enforcement attention than others. But prosecutorial discretion is also not unlimited. A President can’t simply make a blanket declaration that he won’t enforce part or all of a law he doesn’t like. He and the AG are effectively decriminalizing an entire class of narcotics crimes, rewriting a law passed by Congress. Imagine if a President decided to decriminalize securities fraud simply by decreeing that the government will devote no resources to prosecuting securities fraud.