People have spilled a lot of ink and pixels on this question today. Mostly they are parsing an OLC memo. But there is a 1982 Supreme Court decision and a great Justice’s commentary sitting in plain sight, and they hold more weight than any OLC opinion.
In Nixon v. Fitzgerald (1982), the Supreme Court heard a civil lawsuit against Richard Nixon, as ex-president, for firing an official allegedly as retaliation for whistleblowing. The Supreme Court, in a 5-4 vote, recognized that the president had absolute civil immunity for official acts, even if those acts allegedly violated the law. The Supreme Court’s analysis was functional, not formal, turning on the practical purposes of immunity. The Court’s main concern was how civil litigation would be a “diversion of [the President’s] energies,” (p. 752) and secondarily, the Court discussed a need for the President to act “fearlessly” in executing official duties (id). This potential “distraction” problem can be reduced or eliminated by waiting to prosecute until after the President leaves office.
On this question, the Court, with five Justices on board, cited an important passage from Justice Joseph Story:
“There are . . . incidental powers belonging to the executive department which are necessarily implied from the nature of the functions which are confided to it. Among these must necessarily be included the power to perform them. . . . The president cannot, therefore, be liable to arrest, imprisonment, or detention, while he is in the discharge of the duties of his office, and, for this purpose, his person must be deemed, in civil cases at least, to possess an official inviolability.” 3 J. Story, Commentaries on the Constitution of the United States § 1563, pp. 418-419 (1st ed. 1833).
However, Story limits the President’s immunity for criminal liability: “The president cannot, therefore, be liable to arrest, imprisonment, or detention, while he is in the discharge of the duties of his office.” First, it’s notable that Story himself — and the Supreme Court — suggested a lesser scope of immunity for criminal than civil litigation. Civil immunity for official acts is made permanent, but criminal protections are only time-bound by the office, and thus appear not be truly “immunity,” but simply delayed criminal liability. Thus, to those who argue that the President is immune for official acts, Story and the Supreme Court implicitly but clearly reject that position.
Story is offering a strong hint about whether a sitting president may not be indicted for official acts. Of course, arrest and detention are not the same thing as indictments, but the problems of distracting and disabling the president are similar. An indictment and criminal trial are similar to arrest. One might suggest that impeachment is just as distracting and debilitating. A key difference is that there is only one body that can impeach and try impeachment (Congress), and each House can check the other (if an impeachment is unwarranted, the Sentate can quickly wind it down).
But in terms of indictments, there are 95 U.S. Attorneys in America, plus state prosecutors and sometimes a special counsel or two. That’s decentralized chaos. Civil suits are also decentralized and distracting, but the liability is much lower than criminal penalties, and judges can cabin the scope of depositions. But in criminal cases, the risk is much greater, and the pressure for the president to be present throughout the trial is much greater. And all you need is one prosecutor, one trial judge, the barest amount of probable cause, and a supportive local constituency, and you can shut down a presidency with a criminal trial or two or two dozen. Once you say a sitting president can be indicted, don’t expect of appellate courts to bail out presidents from grand juries, because appellate courts stay away from second-guessing indictments everywhere else. Once you open the door, it is hard to create a rule for closing it case-by-case.
Keep in mind that the shoe needs to fit the other foot. What if a rogue federal prosecutor — or a state prosecutor in a deep red state — had a crazy theory that Obama had been bribed by the Iranians for the nuclear deal? Or a crazy claim about Fast and Furious? Or a lunatic charge of fraud with his Hawaiian birth certificate? What about the next Democratic administration? Even if the rule was “no state indictments, only federal,” and you assume no federal U.S. Attorney appointed by a president would ever flip sides, you can imagine an ambitious politician prosecutor suddenly flipping sides to move up in a red state. In hyperpartisan, hyperpolarized modern America, we have to worry about an ambitious and opportunisitc prosecutors. (That’s my next history project, The Rise of the Prosecutor Politicians, focusing on the first half of the 20th century).
There are surely exceptions to this rule if the president is a clear and present danger, not in an abstract sense but in a concrete, immediate, violent sense, like shooting people on 5th Avenue. But in cases of abuse of power, the Supreme Court and Justice Story imply that the first step is removal, and then the next step could be indictment.
Mueller shouldn’t indict Trump, not only because of the OLC memos, Justice Story, and the dicta in Nixon v. Fitzgerald. Mueller shouldn’t indict Trump because it is not the best use of his legal, political, and moral capital. Indict folks like Michael Cohen, but for the sake of legitimacy, he should issue a report on Trump, and then let Congress take the next steps.