The federal prison population is on the decline, but a new attorney general who talks tough on drugs and crime and already has indicated a looming need for private prison cells seems poised to usher in a reversal of that trend. Jeff Sessions, a former federal prosecutor sworn in this month as the country’s chief law enforcement officer, signaled at his confirmation hearing and in first days on the job that he sees a central role for the federal government in combating drug addiction and violence as well as in The result could be in an increase not only in the number of drug prosecutions brought by the Justice Department but also in the average length of sentence prosecutors pursue for even lower-level criminals.