A comparison may be helpful: Prosecutors are central to criminal investigations. They run the show once the investigative phase passes into the charging and prosecution phase. In stark contrast, government lawyers are, at most, ancillary to counterintelligence efforts. They are usually non-participants. Their help is necessary if the agents need to seek a surveillance warrant from the Foreign Intelligence Surveillance Court (the FISA court); but even when that happens, the agents do all the surveillance and analysis.

There could be exceptions in which a presumption against recusal is overcome. Let’s say X, who is a close friend of the attorney general’s, is suspected by the FBI of acting as an agent for China. The FBI goes to the Justice Department’s National Security Division (NSD) because the bureau wants to get a warrant from the FISA Court to intercept X’s e-mails. The NSD, of course, answers to the attorney general. In such a case, to avoid the appearance of impropriety, it would be prudent for the attorney general to recuse himself from any involvement in the FISA surveillance — even though FISA surveillance is done in a counterintelligence investigation, so there is no criminal investigation or prosecution.

But barring that highly unusual situation, counterintelligence investigations should not trigger disqualification or recusal of an attorney general unless and until the investigation turns up incriminating evidence that could form the basis for a criminal investigation — and a possible prosecution. If that happens, the attorney general (or any other Justice Department official in a recusal situation) not only should but must apply the disqualification rule, and should recuse himself if the criminal investigation involves the kind of conflict of interest — based on a personal or political relationship — set forth in the regulation.