Last week, prosecutors in the U.S. District Court for the Southern District of New York alleged in court filings that Donald Trump directed his former personal attorney, Michael Cohen, to make hush money payments that violated campaign finance laws. The prosecutors recommended serious prison time for Cohen, and commentators remarked widely that Trump could be facing his own indictment if he were not president, because the Department of Justice has a policy of not indicting a sitting president. But this news highlights a major problem with this policy: statutes of limitations. The intractability of that problem is a compelling argument for why prosecutors must be able to indict a sitting president. Otherwise, a president could escape prosecution for many felonies by running out the clock.

The campaign finance felony Trump may have directed has a five-year statute of limitations, after which time a defendant cannot be tried if he has not been indicted. What if President Trump wins a second term?

Or hypothetically, what if a president had committed such felonies earlier in a campaign, so that the clock would run out by the end of the first term? Should a president be above the law because of the statute of limitations?

Some have argued that the solution is something called “equitable tolling.” In civil cases, like contracts or torts, there are statutes of limitations for a plaintiff to start a lawsuit. This legal deadline makes sure that plaintiffs give defendants adequate notice, that witnesses’ memories are fresh, and that justice is served and not delayed. The clock can be tolled—the deadline can be extended—if, for example, the defendant engaged in fraud or deception, which induced the plaintiff to miss this deadline. Equitable tolling is rare, but it is firmly established in civil litigation.

Should a president be above the law because of the statute of limitations?

Over the past few days, commentators have suggested that the same principle should apply to the criminal prosecution of a president: that the statute of limitations might automatically toll because of the possibility of presidential immunity from prosecution. In fact, the Office of Legal Counsel’s legal opinion that the president should not be indicted relies on “a court’s possible authority to recognize an equitable tolling” to allow for a postpresidential criminal case to go forward notwithstanding the statute of limitations.

But can courts actually equitably toll a criminal statute? The OLC acknowledged in a footnote that equitable tolling “is invoked only sparingly, in the ‘rare situation where [it] is demanded by sound legal principles as well as the interests of justice.’ ” In fact, the OLC couldn’t even cite a single case where a court granted it to prosecutors. Rather, the OLC memo cited three appeals court cases: two criminal cases that discussed the possibility only in speculative dicta, and one civil case. Even the cases’ dicta give no indication that it would apply in something like a presidential immunity case. Some cases have involved specific tolling statutes for criminal fugitives, but that is not the same thing as equitable tolling, and those statutes do not apply here. Legal scholars have struggled to identify a single precedent in which a federal court equitably tolled the statute of limitations for any criminal defendant. In fact, the term “equitable tolling” comes up so rarely in the legal literature in connection to criminal prosecution, it appears to be something more imagined than real.

The bottom line: It is far from clear that equitable tolling for criminal prosecution exists even in the clearest circumstances.

The OLC memo’s reliance on something that might not exist does not inspire much confidence in its overall reasoning or research.

Additionally, even if criminal equitable tolling were a thing, how would a court know when to invoke it? In a civil context, there are concrete obstacles—like the defendant’s fraud or the plaintiff having been imprisoned—that allow a court to stop the clock. What would be the concrete event for a court to stop the clock for a president?

Some commentators assume the tolling would be automatic. Why? No federal court has ever ruled specifically on presidential immunity, so it’s not a matter of settled precedent. The OLC memo is not law. If federal prosecutors decline to indict because they have an internal policy, then that was their own decision, their own (potentially silent) inaction. Such a defendant could easily object that equitable tolling doesn’t—and shouldn’t—apply, and that he should be protected by the statute of limitations like anyone else. Why should a court hold a prosecutors’ silent inaction against a defendant, even a presidential defendant?

Second, let’s say Mueller or the Southern District of New York wants to bring an indictment, but the effort is blocked by the attorney general because of a view that sitting presidents are immune. Even if this effort became public, Trump would not have to invoke presidential immunity; it would have been invoked for him by the attorney general. When a tolled case ultimately went forward, a court could still say that it was not the president’s fault that prosecutors internally disagreed on policies and sat on indictments. The president could later argue that immunity wasn’t settled law and wasn’t something he ever asked for. It would be the prosecutors’ failure to bring a timely indictment and to seek a judicial ruling on this constitutional question—not the president’s—and the president shouldn’t be punished for it, the argument would go. It might be unclear whether the DOJ declined to indict for constitutional reasons, lack of evidence, or other discretionary reasons.

One solution might be for a prosecutor to issue a report stating, “but for presidential immunity, we would seek an indictment.” This would serve to give notice to the president of the allegations and notice to the courts of the reasons. It would give the president the opportunity to waive his rights under the statute of limitations, and if he did not, a court might be more likely to toll and pause the clock. However, such a report potentially could be suppressed by the attorney general, and it is still doubtful whether such a statement would be enough to toll.

And if such a statement is permissible, why would an actual indictment be any more burdensome on a president? If prosecutors can write such reports saying that a defendant would otherwise be indicted, why not have an actual indictment while delaying the trial? Indictment with delayed trial is consistent with the original Framers’ writings. For example, in Federalist No. 69, Alexander Hamilton wrote:

The President of the United States would be liable to be impeached, tried, and, upon conviction of treason, bribery, or other high crimes or misdemeanors, removed from office; and would afterwards be liable to prosecution and punishment in the ordinary course of law.

Prosecution here might likely refer to the trial. The Framers did not discuss indictments, and there is no sign that they were concerned about indictments as a burden. As long as prosecution-as-trial is delayed, this procedure would be consistent with their vision. (Walter Dellinger and Andrew Crespo have offered deeper analysis on this approach.)

If statute-of-limitations concerns allow sitting presidents to be indicted in some cases with short statute-of-limitation deadlines, then why not indict in cases with longer statutes of limitations? The argument against the burdens is no longer compelling, and crimes with longer statutes of limitations tend to be more serious felonies. Prosecutors must be able to bring indictments for the sake of giving defendants fair notice of the allegations and for the sake of the public. If federal prosecutors have solid evidence that Trump committed a serious felony, the DOJ has a duty to indict a sitting president.

Trump’s attorney general might still try to block such an indictment anyway, but let’s be clear: That attorney general may have to explain under oath his reasons for impeding justice, and presidential immunity is simply not an adequate answer.