Of a million things President Obama could use his second term in office to fix, he has maybe 10 slots — 10 real chances to advance the debate about a topic, even to advance policy, even while Washington is at its sclerotic worst. Drug law reform has always been on the president's to-do list. This I know from a series of conversations with some of his senior policy advisers during the first term. Because Obama's Justice Department has not stopped enforcing federal drug laws even as Americans are evolving quickly on the issue, and because Obama himself has not yet used one of those presidential attention-getting arrows he has, my prediction that he would move in his second term to attack the prison-drug-race nexus has been dismissed as wishful thinking, or, worse, something I just made up.

The drug war is grossly destructive for many reasons: the effect on black families (and increasingly, white families), the cartel violence in Mexico created by U.S. demand, the searing effect that drug policing has on inner cities, the billions of dollars a year spent with virtually nothing to show for it, and many more.

Today, Attorney General Eric Holder will take the first significant step to mitigate one of the most unjust parts of the system: mandatory minimum sentences that almost arbitrarily end meaningful lives for those who get slapped with them. Fear of black people and the need to calm the nerves of white suburbanites provide ample ammunition for white politicians in the 1970s; the crack "epidemic" reupped panic and triggered a federal response in the mid 1980s. The laws made it easy to justify imprisoning large numbers of young black men.

Judges could not consider the quantity of the drug involved, or the circumstances, or the level of violence associated with the crime. This neat little summary eludes many important deviations, however. One argument in favor of reducing judicial and prosecutorial discretion was that it would force the courts to treat people of different races more equally during sentencing. But the laws themselves, and their enforcement, never lived up to to the hope. Mandatory minimums for meth are now attacking poor white families.

According to Reuters, Holder plans to say that the Justice Department won't charge "certain low-level nonviolent drug offenders who have no ties to large-scale organizations, gangs, or cartels" with the type of offense that would trigger a mandatory minimum. Having NO ties whatsoever may be a rather tough burden for someone to prove, because people almost always buy their drugs from other people, and just what a "large-scale" cartel is is not clear.