If mandatory minimums are unjust, why doesn't the president commute such sentences?

Have you ever read an opinion article with which you’re in general agreement but find yourself disagreeing sharply with some of the writer’s points? That’s how I felt about today’s Wall Street Journal article by Judge Michael Ponsor about sentencing.

Judge Ponsor hails the 2010 Fair Sentencing Act, which reduces the discrepancy between sentences for crack cocaine and powder cocaine, and the 2005 Supreme Court decision in U.S. v. Booker, which overturned the federal sentencing guidelines.