When President Trump fired Jim Comey, a number of commentators likened the sensational development to the Saturday Night Massacre. The comparison seemed fair enough: a president in each case directed the firing of the senior law enforcement official in charge of an investigation that reached into the Oval Office. In the Nixon case, regular order was restored. Leon Jaworski replaced Archibald Cox as the special prosecutor investigating Watergate. Nixon paid dearly for his acts of obstruction, which included the attempted use of intelligence agencies to scuttle the inquiry. At some point, he accepted that the jig was up and the law enforcement process ran as it should, with the appropriate independence and professionalism.

Following Comey’s dismissal in the current administration, the deputy attorney general appointed a special counsel and President Trump nominated, and the Senate will likely confirm, a highly respected and experienced new FBI director. Something like regular order has seemingly come to pass.

Appearances may have deceived, however. One need only look at the events of this last week, culminating in the leaks to the Washington Post that raised questions about Attorney General Jeff Sessions’ account of his dealings with campaign representatives of the Russian government. The press reports on those dealings followed the President’s extraordinary attack on Mr. Sessions in an interview with the New York Times, in which Mr. Trump went out of his way to express his loss of confidence in Mr. Sessions. He complained about the attorney general’s recusal in the Russia matter, and then went so far as to say that, had he known of this likelihood that Mr. Sessions would recuse, the president would not nominated him. Put another way, Mr. Trump would not have chosen a nominee who intended to follow the standards for recusal set out in departmental regulations. And then, in a foreshadowing of the Post story to come, the president sternly criticized as “bad” the answers Sessions offered in his testimony to Congress on his contacts with Russian officials.

These assaults alone constituted a blow to the standing of the Department of Justice. It is hard to recall any similar instance in which a president went so savagely after a member of his cabinet, and certainly not the attorney general of the United States. He also attacked the deputy attorney general, denounced Mr. Comey as a serial liar, and cast aspersions on the integrity of the Mueller investigation.

Mr. Sessions responded that he would not resign. On the very following day, the Post reported in greater depth on his conversations with the Russian Ambassador to the United States and the doubts these contacts raised about the completeness or truthfulness of his testimony to Congress. Both current and former officials were the sources for the story. Who, and why now?

It is not out of the question that these leaks originated out of the White House, or at its direction, to put additional pressure on Mr. Sessions to resign. Of course, if he did resign, Rod Rosenstein will remain acting attorney general. Also, a new attorney general nominated by Trump would have to win Senate confirmation. It seems unlikely, more now than even a few weeks ago, that the Senate would allow Mr. Trump to have an attorney general who seemed ill-equipped, or would not commit, to resist pressures to intervene inappropriately in the Russia matter. Any number Republicans normally inclined to defer to the presidential choice would have to be affected by what they have observed of Trump’s behavior toward Mr. Sessions.

But from the perspective of the Trump legal team, there are still advantages to a White House coup against Mr. Sessions. It is clear that lawyers around Mr. Trump share his view that Mr. Mueller's investigation is veering out of control. They see his office as riddled with conflicts and politically biased, and they question Mr. Mueller’s own impartiality because of his professional association over the years with Mr. Comey. On this view, Mr. Trump and his legal advisers might see the current state of affairs as the worst of all worlds, not easily remedied but also intolerable.

With Mr. Session’s recusal, only Mr. Rosenstein is in a position to exercise supervision over Mr. Mueller and to entertain complaints about his conduct of the inquiry. But as Mr. Trump made clear, he also distrusts Mr. Rosenstein. And he and his legal advisers might well believe that, having suffered from exceedingly harsh criticism over his role in the firing of Mr. Comey, Mr. Rosenstein will be unwilling to intercede in any way in Mueller’s activities. A new attorney general does not have to be wholly subservient to presidential dictates to represent an improvement in Mr. Trump’s situation.

Of course, Mr. Trump could fire Sessions at any time or apply even more pressure on him to resign. What is chilling about this particular episode, if the White House is the source of the leaks, is the misuse of classified intelligence to incapacitate the department's leadership. Watergate analogies come cheap, but this one is apt. Nixon and his senior staff tried to engage the Central Intelligence Agency, but with only brief success, in pressing the FBI to limit the investigation. The CIA leadership made a pass at following this order and then stepped back, as did the FBI Director Patrick Gray. Should the White House of the current administration have misused classified intelligence to alter the chain of command at the Department of Justice in a bid to influence the course of the the Russia investigation, it would have also abused its relationship to the intelligence community—except that this time, this need not have occurred with the willing participation of the intelligence community leadership.

Now the president has effectively denied any such abuse. On Saturday, he tweeted a denunciation of the leaks about Mr. Sessions. Observers will make what they may of this complaint, but some will recall that, in the “unmasking” matter, this administration has once before improperly shared intelligence information outside normal procedures to achieve a political objective. In another action involving the intelligence community still closer in kind to the Watergate experience, the president tried to recruit the support of the directors of the Office of Director of National Intelligence and of the National Security Agency in curbing Mr. Comey’s investigation of former National Security Adviser Michael Flynn.

All this is far from regular order, and worse. And from the last week to this one, this continues. Mr. Trump tweeted Monday morning that his attorney general was “beleaguered,” without acknowledgement that he, the president, had helped bring about this state of siege with his attacks on Mr. Sessions. But he apparently meant, too, that Mr. Sessions in his weakened condition was not doing this job, which in Mr. Trump’s view appears to require a criminal investigation of Hillary Clinton. In this one tweet, the president both assailed his attorney general and declared his wish for a specific criminal prosecution—of his 2016 general election opponent. It is difficult to cite a starker example of the trashing of a norm in a president’s relationship to the Department of Justice.

Similarly troubling, if less dramatic, is the recent report that the president and with White House counsel met with his nominee for United States Attorney for the District of Columbia, Jessie K. Liu. Presidents do not routinely interview U.S. attorney nominees. There are 93 such nominees, and the president can hardly speak to all of them. The natural question is: which would a president decide to interview, and why? President Trump has spoken to only Liu.

One can only guess at the reasons. But it is worth noting that when Congress pursues criminal contempt for witnesses declining to provide subpoenaed testimony or documents, it must rely on the U.S. Attorney for the District of Columbia to bring the matter before a grand jury and to prosecute. These cases arise in conflicts with the Executive Branch when the president has directed a subordinate to withhold cooperation on a claim of executive privilege. In the recent part, U.S. Attorneys have declined in these circumstances to put the facts before a grand jury or bring charges.

In this administration, with major congressional investigations pending, the U.S. Attorney may find herself in this position. Did that topic come up in a discussion that the putative nominee had with the President or his legal advisers? It may not have, but then the question is: what is the reason for the meeting?

Ms. Liu appears highly qualified for the position and there is no cause to doubt her ethics. The intent of the president in having her, of all U.S. Attorneys, to the Oval office is a different question. It is possible that the president said nothing of consequence in the meeting but wanted to take the nominee’s measure and build the personal rapport he failed to achieve with Mr. Comey—but not for want of trying. And there is ample cause for concern about the president’s motivation for personal relationship-building with senior law enforcement.

This motivation may be just what it appears to be: Mr. Trump’s wish to establish a new accountability—the highest accountability of the law enforcement officials to him, expressed by the demand for personal and political loyalty. Mr. Sessions sinned by recusing; Mr. Comey, by spurning the hand of friendship; and Mr. Rosenstein appointed Mueller and (so the president believes) hails from a city full of Democrats. Mr. Sessions is under open attack from the president and is now weakened further, and perhaps fatally, by an intelligence leak. Mr. Comey was fired and the president has since accused him of engaging in blackmail and lying to the Congress. Trump, echoed by his lawyers, has denounced as illegitimate the Mueller investigation. And along the way the president has decided that he should have a chat with his nominee for U.S. Attorney for D.C.

This accountability seems to be one-sided. When Saturday morning came, the president was up and tweeting, and he declared his pardon power to be “complete.” Did he mean he could pardon himself, even to end an investigation he may have reason to fear or dislike? His decision to bring up the question of his power to make a point only of its “completeness” suggests he may have— which would make Mr. Trump the first president to answer serious questions about the rule of law in his government by declaring that he is above it. When Richard Nixon told David Frost in 1977 that “when the president [breaks the law], that means it is not illegal,” he was long out of office and no longer able to do harm.

In a curious but perhaps revealing public stance, the president’s recently named communications director and one his lawyers, Jay Sekulow, appeared on Sunday shows this weekend to deny that the president or his lawyers would consider pardons for conduct in the Russia matter. He argued that no pardons were required because no offenses had been committed. Mr. Sekulow, declared that, "We're not researching the issue, because … there's nothing to pardon from." But this seemed to confirm by implication that Trump and his legal team would consider a pardon if there was something “to pardon from.”

The grave danger in the president’s conception of the Department of Justice, and of his relationship to it, arises from the same source as other risks of his governing style: his ethics. He cannot distinguish between the public interest and his own, and so he cannot or will not appreciate how the observation of that distinction is crucial to the integrity of government institutions. This is a unique threat to the impartial and professional administration of law enforcement.

When President Gerald Ford chose Edward H. Levi to lead the Department of Justice after Watergate, he told his prospective nominee that, as he expected a primary challenge, he could not offer job security. But, as Ford further recalled years later, "I could and did promise Ed that no politician would encroach on the Department. I wanted him to protect the rights of American citizens, not the President who appointed him."

This is not the view of the current president, who is flouting regular order and who may try to do what he can to rein in the Department of Justice and then manage it on the Watergate model.