The real solution is for Congress to reform federal sentencing policies through legislation and for state legislatures to follow suit. That might seem like a long shot given the political gridlock in Washington, but criminal justice reform has emerged as a rare issue uniting interest groups on the right and the left. The New York Times reported last week on the new Coalition for Public Safety, an odd bedfellows conglomeration of the Koch brothers, the Center for American Progress, the ACLU, Americans for Tax Reform and others, dedicated to reducing prison populations. It's an issue that has the potential to unite liberals, libertarians and fiscal conservatives and has already led to several bi-partisan legislative efforts. If they eventually succeed and help the nation reverse a generation of damaging and ineffective policies, Mr. Holder's advocacy will have a lot to do with it.