Here’s some unsolicited advice for President Donald Trump: Don’t listen to any lawyers who might tell you that you can pardon yourself, or even that it’s a close legal question. You can’t — and no court is going to rule otherwise.

There’s a decent historical argument about why, but it’s beside the point. The bottom line is that if the president could pardon himself, we would no longer have a republic, nor a government of laws rather than men. We would be a dictatorship, not a democracy.

You know that. Americans know it. The Supreme Court knows it. Now let’s move on.

The very idea of self-pardon is the kind of silly technicality that non-lawyers think lawyers engage in all the time. I’m not going to offer a full-throated defense of the legal profession, but we’re not really that dumb or bad — at least not usually.

The idea of the pardon power itself is old, going back at least to medieval England and the king. It is based, roughly speaking, on the idea that the king is in charge of administering the common law, and, therefore, has the authority to go around that law and issue a pardon or reprieve when it’s desirable to do so.

This made some sense in a system that wasn’t democratic and imposed the death penalty as punishment for all felonies, including relatively minor ones.

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In theory, the justification could be mercy, that most Christian of virtues. In practice, kings sometimes issued pardons to political allies, or in exchange for compensation, or to get military conscripts.

As a result, as early as 1311 (you read that right), Parliament forced the king to promise that he would only pardon “by process of law and the custom of the realm.” The idea was to rein in the pardon power, making it into an instrument of law, not of arbitrary royal prerogative.

Given that worry about the anti-legal nature of the pardon power was already more than 450 years old when the Founding Fathers drafted the U.S. Constitution during the hot summer of 1787, it’s a bit surprising that the pardon power even made it in.

In Philadelphia, the more rights-oriented republicans, like George Mason of Virginia, questioned the whole idea of the pardon power. The more pro-executive participants, like Alexander Hamilton and James Wilson, managed to get it in, albeit without much debate. The idea was that pardons served mercy and could be expedient.

No one so much as hinted that the president could pardon himself. The king, after all, was above the law — he would never have to pardon himself because he could never be brought before one of his own courts. The president wasn’t above the law.

At the North Carolina ratifying convention, the future Supreme Court justice James Iredell gave a lengthy defense of the need to have a merciful pardon power somewhere.

In the speech, Iredell pointed out that the president wouldn’t be able to pardon an impeachment. The clear implication was that if the president was himself impeached, he could then be criminally tried. Iredell also commented that it was highly unlikely that the president would treasonously pardon a traitor — further reason to believe no one contemplated self-pardon.

But frankly, the history isn’t the point.

The basic problem with self-pardon is that it would make a mockery of the very idea that the U.S. operates under the rule of law. A president who could self-pardon could violate literally any federal law with impunity, knowing that the only risk was removal from office by impeachment.

We have a name for an elected leader who is outside the law: dictator. And dictatorship is fundamentally inconsistent with the republic established by the Constitution. In fact, it’s a little difficult to think of any single idea that would more grossly violate the rule of law than a president free to break any and every law and then wave a get-out-of-jail-free card.

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Of course, it’s true that no court has ever held that the president can’t pardon himself — because no president has so outrageously tried to flout our basic constitutional principles.

We can thank God for that. But more immediately, we can thank a constitutional structure that is designed to limit the institutional power of any single branch of government.

And that’s why I can predict with complete confidence that no court would uphold a presidential self-pardon. To do so would be to render the courts essentially useless as checks on the executive, to say nothing of Congress, which passes the laws in the first place.

This isn’t a normal legal problem for courts to resolve by weighing plausible, competing arguments. It’s the whole ball of wax: the survival of constitutional government. The courts will treat it as such.

If the president uses the pardon power to end investigations against his cronies and protect himself, that’s a political problem that would call for a political solution, namely impeachment.

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But if the president were to try to pardon himself, the courts would simply rule that the pardon was ineffectual. Once out of office, by impeachment or by the end of his term, the president would be subject to criminal charges.

It won’t come to that, I believe.

The Republic isn’t about to turn into a dictatorship. To make sure things stay that way, no one should talk as though self-pardon is a realistic possibility. It isn’t — not in a functioning democracy with the rule of law.

Noah Feldman is a Bloomberg View columnist. He is a professor of constitutional and international law at Harvard University and was a clerk to U.S. Supreme Court Justice David Souter.