Ronald Rotunda is a professor at Chapman University’s Fowler School of Law.

Nearly two decades ago, then-independent counsel Kenneth Starr asked me to evaluate whether a federal grand jury could indict a sitting president — in that case, Bill Clinton. My answer — that such an action would be permissible — was recently unearthed in response to a Freedom of Information Act request from the New York Times, and it may have relevance for a new special counsel and the current president.

(Adriana Usero/The Washington Post)

My fundamental conclusion remains intact: Nothing in the Constitution would bar a federal grand jury from returning charges against a sitting president for committing a serious felony. But — and this is a big but — differences between the Clinton situation then and the investigation of President Trump now mean that where Starr had the authority to indict Clinton if he chose, Mueller most likely does not possess the same power.

On the underlying question of whether the Constitution bars indictment of a sitting president, no previous case is directly on point. The Justice Department has taken a different view than the conclusion I reached — both beforehand, during the Watergate investigation, and afterward, at the end of the Clinton administration. But the history and language of the Constitution and Supreme Court precedents suggest that the president does not enjoy general immunity from prosecution.

First, the framers knew how to write a clause granting such immunity when they wanted to. Members of Congress enjoy “privilege from arrest” in civil cases when going to and from Congress (now irrelevant because we no longer use that procedure) and may not be criminally prosecuted for “any speech or debate” in Congress. If the framers wanted to protect the president from prosecution while in office and to make impeachment the sole mechanism for proceeding against a president, they could and would have said so.

Second, some argue that criminal prosecution would distract the president and make him unable to perform his duties. During Watergate, Richard Nixon’s lawyers argued that “if the president were indictable while in office, any prosecutor and grand jury would have within their power the ability to cripple an entire branch of the national government and hence the whole system.” The Supreme Court never reached that question, and Nixon left office without being indicted.

In my view, questions about “crippling” the government are not compelling, and the precedents in favor of the power to indict a sitting president were strengthened with the Supreme Court’s ruling that a private sexual harassment lawsuit against Clinton involving alleged conduct before he took office could go forward even during his presidency.

As I wrote in the memo to Starr, “If the president is indicted, the government will not shut down, any more than it shut down when the Court ruled that the president must answer a civil suit brought by Paula Jones.” In addition, the 25th Amendment offers another answer to the government-could-not-proceed objection, by providing a mechanism to keep the executive branch running if the president is temporarily unable to discharge his powers. In this country, no one is above the law.

Nonetheless, there is a significant — in fact, likely dispositive — difference between the Clinton situation and that facing Trump. Starr served as independent counsel under a now-defunct statute. By contrast, special counsel Robert S. Mueller III serves under Justice Department regulations put in place after the independent counsel law expired.

This is not a technical distinction but one that I discussed in my memo, distinguishing between the independent counsel statute and the regulations such as those establishing Mueller’s office.

And this difference has enormous implications for Mueller’s power. Supreme Court cases going back 150 years emphasize that the president retains complete authority to control federal criminal prosecutions. Without a statutorily appointed special counsel given special tenure, Trump could fire anyone who tried to indict him.

Moreover, the regulations governing Mueller mandate that he “comply with the rules, regulations, procedures, practices and policies of the Department of Justice.” They permit removal of the special counsel for “good cause, including violation of Departmental policies.”

As Clinton was about to leave office, his Justice Department’s Office of Legal Counsel ruled that the president could not be indicted. Is this legal opinion a departmental policy that binds Mueller? It would seem so, given that OLC’s stated function is “to provide controlling advice to Executive Branch officials on questions of law” (emphasis added). If that creates a Catch-22 situation in which a special counsel can never proceed against a president, my answer is: I don’t write the rules, I just read them.

As interesting as this debate is, it also strikes me as entirely premature. In my assessment, the “case” against Trump right now amounts to a mountain of innuendo built on a foundation of loose sand. The facts so far do not come close to making an obstruction case against the president, and for now there is no evidence that he engaged in any underlying crime.

If and when Mueller comes up with something that might create an indictable case, though, he is apt to run into serious questions about the limitations of his office, questions that Starr did not face.