It is only natural, then, that a president will want his power wielded by his own appointees, whom he trusts to carry out his policy program. And it thus follows that, when there is a transition between administrations that see the world, and the Justice Department’s role in it, as differently as the Obama and Trump administrations, there will be sweeping turnover, carried out rapidly.

That is as it should be.

Yes, it was not uncommon in the pre-Clinton era that new presidents permitted sitting U.S. attorneys to continue through the transition of administrations to the completion of their four-year terms. But that is a bygone time, when the federal government was not nearly as expansive, the role of federal law enforcement was far more modest, and litigation did not have as imposing a role in settling society’s disputes.

Nowadays, there is unprecedented policy consequence in the execution of federal law enforcement, as much in the civil as in the criminal arena. It matters more than ever that the president has his appointees, who are chosen because they support his policy preferences. If Donald Trump has determined that the immigration laws must be enforced, and has won an election with that as a signature issue, why would he retain the U.S. attorneys Barack Obama appointed — prosecutors plainly sympathetic to Obama’s non-enforcement policies?