One of the most remarkable stories of 2017 was the extent to which President Donald Trump was prevented from executing his many pledges—both on the campaign trail and in office—to violate the law. As predicted, courts, the press, the bureaucracy, civil society and even Congress were aggressive and successful in stopping or deterring Trump from acting unlawfully.*

But will these checks continue to work in the new year?

The biggest concern lies in threats to Special Counsel Robert Mueller’s investigation of “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump,” and related matters. The worry is that Trump or his senior associates may have engaged in law-breaking or some form of electoral corruption, and could get away with it. The Mueller investigation involves the executive branch investigating itself, including the president. The president sits atop the executive branch and has made clear from the beginning that he detests the Mueller investigation. In recent weeks anxiety that Trump may kill the investigation has reached a fever pitch as the president and other partisans have ratcheted up attacks on Mueller, the Justice Department and the FBI. And that was before Trump a few days ago claimed the “absolute right to do what I want to do with the Justice Department.” (He also said many times in the interview that he thought Mueller would treat him fairly.)

We don't yet know whether Trump acted unlawfully or wrongfully, or how close (if at all) Mueller will get to him, his business or his family. But Mueller’s probe appears to be “fast approaching a critical crossroads.” This year, we will find out whether Mueller has damaging goods on the president. Let’s assume that the investigation goes in a direction that Trump is inclined to shut down. I believe that what we learned in 2017 should give us confidence in 2018 that Trump will not be able to terminate the Mueller investigation.

Begin with how well the system has worked thus far. Attorney General Jeff Sessions infuriated Trump when he followed Justice Department rules and recused himself from the investigation. Deputy Attorney General Rod Rosenstein infuriated Trump when he followed Justice Department rules and appointed Robert Mueller as special counsel after Trump fired FBI Director James Comey. These men took the proper steps despite the allegiance that political appointees typically feel toward the president who appointed them. They did so because they are embedded in and charged with running an institution with rules and norms that they feel personal and professional responsibility to abide by and uphold. This is a key point, to which I will return.

The Sessions recusal, which set the Mueller investigation in motion, was especially remarkable in light of the attorney general’s decades in politics and special fealty (at least at the time) to the president. Ever since the Mueller investigation began in May, Trump has, in a truly unprecedented and vicious fashion, bashed Sessions, Rosenstein, Mueller, the department for which they work and Mueller’s “witch hunt.” And yet, despite clear opposition from the man ostensibly in charge of the executive branch, the Mueller investigation has proceeded aggressively and without interruption. It has proceeded, moreover, through the transition atop the FBI from the man Trump fired (Comey) to the man Trump chose to replace him (Chris Wray). Wray shows every indication thus far of working closely with and fully supporting Mueller.

In short, the political appointees in the Justice Department who are connected to the Mueller investigation have shown that they follow the rules and norms of the department despite the president’s wishes otherwise. This is all an amazing (though widely unappreciated) testament to the DOJ’s independence and the rule of law. I think the mechanisms that worked so well in 2017 will keep working to see the investigation through, no matter what steps Trump takes to stop it.

If Trump wished to stop the Mueller investigation, he couldn’t just tweet a declaration that it is over. The investigation is guided by a set of Justice Department regulations that Rosenstein deemed “applicable to the Special Counsel” in his appointment order. (The regulations give control over the Mueller investigation to the attorney general—who, because Sessions is recused, is Rosenstein, the acting attorney general for this purpose.) Rosenstein in theory could, under 28 CFR 600.7(b), order Mueller not to pursue “any investigative or prosecutorial step,” but only if Rosenstein concluded, after giving Mueller’s views “great weight,” that Mueller’s proposed step was “inappropriate or unwarranted under established Departmental practices.” Rosenstein could also in theory remove Mueller from office under 28 CFR 600.7(d), but only for “misconduct, dereliction of duty, incapacity, conflict of interest, or for other good cause, including violation of Departmental policies.” If Rosenstein took either course, he would need to justify his actions in writing to Congress.

These are very demanding legal criteria for Rosenstein to terminate Mueller or elements of his investigation. But Rosenstein does not think Mueller is close to meeting them. To the contrary, in public testimony he has consistently and unambiguously proclaimed that he is satisfied with the conduct of Mueller’s investigation. Of course, Trump is Rosenstein’s boss and he might try to order Rosenstein to fire Mueller or terminate parts of the investigation that he doesn’t like. (Terminating Mueller by itself won’t stop the investigation; Wray would carry on and the next acting attorney general would need to appoint a successor to Mueller—and would be under enormous pressure to appoint someone of unquestioned independence.) But Rosenstein cannot, and won’t, do either thing, even if ordered, unless he can justify those things under the regulations. And the facts just won’t support a conclusion that Mueller has engaged in misconduct warranting termination or (absent a development I cannot now fathom) that Mueller egregiously violated Justice Department practices that would warrant termination of an element of the investigation. Rosenstein would thus surely say no to Trump’s order, for the same reason that he and other political appointees in the Justice Department have been ignoring Trump and following the rules for the past year. And then Trump would fire Rosenstein.

That would leave Trump with three options to shut down Mueller.

First, after he fired Rosenstein, Trump could keep firing Rosenstein’s replacements in the Justice Department until he finds someone who—in defiance of the special counsel regulations and the terms of Rosenstein’s appointment of Mueller—would be willing to terminate both Mueller and the elements of the investigation Trump doesn’t like. I doubt Trump could find a Senate-confirmed official (as the law requires) to replace Rosenstein and do these things. Any such person would be constrained by the same organizational, professional and reputational norms that have influenced Rosenstein and others. And even if Trump were able to find a person of so little integrity to take the professional reputational hit inherent in such law- and norm-defiance, the outcry and controversy within and outside the Department of Justice would be enormous and almost certainly destructive of Trump’s presidency.

Second, Trump could invoke Article II to bypass or invalidate the Justice Department regulations and the Mueller appointment order to fire Mueller and shut down the parts of the investigation he does not like. This takes us to contested constitutional issues that are hard to explain without much more space. Suffice it to say that while Trump might be able to do some of this lawfully, it would be enormously controversial, legally and politically. I doubt he could find subordinates willing to execute the order, and if he did, he would be committing political suicide.

Third, Trump might try to pardon everyone involved. This would almost certainly be lawful under Article II with regard to everyone except possibly the president himself, and in any event it would likely be efficacious because it would not be subject to collateral review. (The Office of Legal Counsel once concluded with little analysis that the president cannot pardon himself. There is little definitive law on this question.) But pardons by themselves wouldn’t stop the Mueller investigation from continuing. They wouldn’t stop the Justice Department from reporting Mueller’s findings to Congress under the special counsel regulations. They wouldn’t stop related state prosecutions. And they would be political dynamite that would destroy Trump’s presidency.

Note that my confidence that Trump cannot “get away with” killing the Mueller investigation ultimately rests on two factors: the good faith of Trump political appointees to follow the law and the political reaction if Trump acted to try to circumvent their good-faith adherence to the law. These might seem like weak reeds. But at bottom, as we learned in Watergate, they are what make constitutional principles operate against a president. As David Ignatius put the point last summer: “The protection against lawless behavior in a democracy, in the end, isn’t the institutional framework set forth in our Constitution, but the will of public officials to make that system work—and the ability of the public to put aside factional differences and support the rule of law.”

In 2017 these mechanisms worked remarkably well. Political appointees followed the rules, and numerous Republican members of Congress, those most sensitive to politics and the wishes of the people, signaled strong support for the Mueller investigation. A "small but vocal group of conservative lawmakers," bucked up by Fox News and the like, have started aggressively attacking Mueller, though a much larger group of Republican members of Congress, including senior Republican leaders, continues to express support. We should not expect Republican support for Mueller to be any more uniform than it was for Archibald Cox and then Leon Jaworski during Watergate. And yet I continue to believe, as I wrote last June, that if Trump tries to shut down Mueller through any of the mechanisms above, “Congress would rise up quickly to stop the President, and the pressure on the cabinet would be enormous as well.” I think that enough important Republican members of Congress would turn on Trump to cause him serious political damage.

The ultimate check here, as always, is the American people. Right now they support Mueller and his probe. We have midterm elections in 11 months that at the moment look bad for the Republicans. Any Trump shenanigans to stop Mueller would, I think, make the shellacking even worse. At the end of the day, the voice of the people is what ensures that Congress does the right thing and that the president does not defy the law.

While Trump cannot kill the Mueller investigation, he may have more success in discrediting it. This is the real point of the attacks and threats by Trump and his supporters and media proxies. The goal is to delegitimize Mueller for the same reasons that Bill Clinton’s proxies tried to discredit Ken Starr: to shape the politics of impeachment or, possibly in Trump’s case, of massive pardons. No matter what Mueller discovers, it is highly unlikely (indeed, almost unthinkable) that he would seek to prosecute the president. (The official DOJ view, which I think binds Mueller, is that a sitting president cannot be prosecuted; but even if there is wiggle room around this rule, it would be unwise to seek to prosecute a sitting president, and Mueller is not unwise.) A more likely worst-case scenario for Trump is a Mueller prosecution of his associates and possibly of Jared Kushner, combined with a thorough report by Mueller that details what he found and (if the facts support it) that is highly critical of Trump in ways that might warrant impeachment. The attacks on Mueller are preparations for those possible battles ahead. The American people are both audience and judge for those battles. I continue to believe that they will speak loudly and clearly enough to ensure that the matters Mueller is investigating will be seen through to the end.

_____

* If you are skeptical about my claim about Congress in the first paragraph, recall that the Republican-controlled first branch has been seriously investigating Russian interference in the election (at least in the Senate) and tied Trump’s hands on Russia sanctions, and that leaders of Trump’s party have pushed back against the first immigration order, hints of return to black sites, and threats to fire Sessions and Mueller. Yes, some of the more partisan Republicans are now attacking Mueller; and the House Russia investigation has ranged from uneven to poor. But against the baseline of modern conventional wisdom about how separation of powers works, the Republican Congress has been extraordinarily vigilant in checking Trump’s illegal tendencies, especially in the honeymoon first year. South Dakota Sen. John Thune, the chairman of the Senate Republican Conference, said in August that it was a “good thing” that Congress was pushing back against Trump. “It’s important that Congress assert its authorities under the Constitution and be an equal branch of the government,” he added. This sentiment, and the actions animated by it, are highly unusual from a Congress controlled by the president’s party.