It’s a Justice Department rule and he’s far from the first attorney general to recuse himself from an investigation.

Attorney General Jeff Sessions has reportedly received word from new White House chief of staff John Kelly that his job is safe. That was good news following President Trump’s hints that he planned to replace Sessions with someone who would not recuse from the Justice Department’s Trump-Russia investigation.

Such a move would sow doubt in the investigation’s outcome and imperil the public’s faith in the administration of justice. Simply put, the investigation must continue without real or perceived political interference. 

Yet Trump’s recent public haranguing of Sessions for recusing himself from the Trump-Russia investigation has been alarming enough. In the 2017 version of his campaign’s “lock her up” chant, Trump took to Twitter complaining that Sessions hadn’t done enough to investigate “Hillary Clinton crimes” — another investigation from which Sessions has removed himself.

As both Republicans and Democrats have recognized, Sessions made exactly the right call in formally stepping back from these investigations.  

Sessions had no choice but to recuse. And that’s not just because of his two meetings with Russian Ambassador Kisilyak, which created an appearance of impropriety after he misled the Senate Judiciary Committee. A Justice Department rule prohibits employees from taking part in an investigation if they have “a personal or political relationship” with anyone who was involved in the investigation or would be affected by it. “Close identification with an elected official, a candidate . . . a political party, or a campaign” is explicitly listed as an example of the type of political relationship that would require recusal. There can be no doubt that Sessions — as the first senator to back Trump’s presidential aspirations and as a member of the Trump campaign’s national security advisory council — fits the bill.

The Justice Department rule is no technical nicety. It embodies fundamental principles of fairness that are the bedrock of our democracy.    

In Federalist 10, James Madison famously noted: “no man is allowed to be a judge in his own cause, because his interest would…