President Trump at a rally in Nashville on May 29. (Mark Humphrey/AP)
Steve Vladeck is a professor at the University of Texas School of Law, co-editor in chief of Just Security, co-host of the National Security Law Podcast and a CNN legal analyst.

“In England,” Alexander Hamilton says in the Federalist No. 70, “the king is a perpetual magistrate; and it is a maxim which has obtained for the sake of public peace, that he is unaccountable for his administration, and his person sacred.” Even if he’s advised by a constitutional council, ultimately, a monarch “is the absolute master of his own conduct in the exercise of his office, and may observe or disregard the counsel given to him at his sole discretion.”

How to proscribe that power — how to vest an executive with enough power to do his job but to prevent an executive from exercising powers of a king — was at the heart of Hamilton’s ruminations in that essay and throughout the debates among the Founders about how to best organize the new republic, especially after the first such effort, the Articles of Confederation, had fared so poorly. They understood, as Hamilton outlines in the Federalist No. 69, that although their new Constitution would create a strong and powerful chief executive, “there is no pretense for the parallel which has been attempted between him and the king of Great Britain,” since, unlike the role of president, a king is “sacred and inviolable.”

Someone ought to tell President Trump’s legal team.

In a pair of extraordinary letters, written in January and published Saturday by the New York Times, the president’s lawyers wrote to special counsel Robert S. Mueller III that, in their analysis, as chief executive, Trump’s actions vis-à-vis the Russia investigation “cannot constitute obstruction, whether viewed separately or even as a totality”; that Trump cannot be indicted for any federal crimes so long as he’s president; that Trump cannot be subjected to a subpoena absent the most exceptional circumstances, even articulating that “the President’s prime function as the Chief Executive ought not be hampered by requests for interview”; that he can fire any executive branch officer “at any time for any reason”; and strongly suggesting that he can pardon himself, writing that “he could, if he wished, terminate the inquiry, or even exercise his power to pardon if he so desired.”

Monday morning, Trump reinforced this suggestion by tweeting the following:

Between them, the letters and the tweet amount to an extraordinary assertion of executive power, leading some to assess that Trump and his lawyers want him treated as if he were a monarch — someone, in Hamilton’s words, “unaccountable for his administration” — for all intents and purposes, above the law. Not to put too fine a point on it, former Justice Department lawyer Harry Litman argued Sunday for the New York Times that “President Trump Thinks He Is a King.” He’s right: The claims being advanced by Trump’s lawyers, if they carry the day, could leave us with an authoritarian, kinglike chief executive — but only if Congress allows it to happen.

The Founders provided Congress with the power to prevent such an eventuality, but there are features of our modern political system that they didn’t account for. And there was nothing they could have inscribed into the Constitution that would compel feckless legislators to act.

Recall how we got here: The American Revolution was sparked, at least in part, by opposition to the tyranny of King George III, a grievance reflected, for example, in the 13 specific complaints lodged against the king in the Declaration of Independence, including the charge that “He has obstructed the Administration of Justice, by refusing his Assent to Laws for establishing Judiciary powers.” The Founders sought to diffuse the state’s authority. But by the time the Constitution was drafted more than a decade later, the weakness of the new government under the Articles of Confederation had driven home the need for a strong central government, headed by a single chief executive, who would have the power, among other things, to supervise the executive branch, veto undesirable legislation, appoint government officers and federal judges and “grant reprieves and pardons for offenses against the United States, except in cases of impeachment.”

Critics objected that this new president looked a whole lot like the old king. In “The Real Character of the Executive,” the 69th of what would come to be known as the “Federalist Papers,” Hamilton pushed back. The reason the president more closely resembled the (presumably inoffensive) governor of New York than the king of England, he argued, had everything to do with the constitutional role contemplated for Congress. After all, it was Congress, unlike the British Parliament, that could override a presidential veto of legislation. It was Congress, unlike Parliament, that would have the power to declare war. It was the Senate, unlike Parliament, that would have to confirm officers and judges nominated and ratify treaties. Whereas the king had broad discretion to prorogue or even dissolve Parliament, the president’s power to adjourn Congress was sharply limited. And the president, unlike the king, was subject to impeachment and removal by Congress for “treason, bribery, or other high crimes and misdemeanors.” Thus, Hamilton concluded, although the new Constitution would indeed create a strong and powerful chief executive, Congress was the check preventing the president from becoming like the king.

In other words, Hamilton believed that the constitutional role guaranteed to Congress would help to ensure that the president could not, in fact, act like a king. This reasoning dovetailed with the broader point James Madison made weeks earlier, writing in the Federalist No. 51 that “the great security against a gradual concentration of the several powers in the same department, consists in giving to those who administer each department the necessary constitutional means and personal motives to resist encroachments of the others.”

“Ambition,” he went on, “must be made to counteract ambition.”

The Constitution, therefore, was designed in a way in which the president would have powers that, if taken to — and beyond — their limits, might indeed resemble those of an absolute monarch. But its authors, Hamilton and Madison among them, maintained that Congress would not only have the ability, but also the incentive, to exercise its own powers in a way that would constrain such a power-hungry president.

What the Founders famously failed to anticipate, of course, was the rise of political parties — and the increasing reality that the federal government today is characterized as much by the separation of parties as it is by the separation of powers. And with a few intermittent exceptions, congressional Republicans have done little to raise alarms about, let alone rein in, the kinds of powers that Trump’s legal team is now asserting.

On Sunday, House Majority Leader Kevin McCarthy (R-Calif.) told CNN that “it’s time to wind this down,” referring to the Mueller investigation — a claim that would sound better if there were any reason to believe Congress had investigated the same matters with comparable zeal. Although four Republican senators joined their Democratic colleagues to advance, out of committee, legislation that would make it harder for the president to remove Mueller without good cause, their bill has languished since — with Senate Majority Leader McConnell (R-Ky.) meekly stating that bringing the bill to the floor for a vote is “not necessary.”

We’re far enough along, though, to know it is necessary. As Barry Berke, Noah Bookbinder and Norman Eisen argue today for The Washington Post, “even if a public official has the authority to take some action, the law still forbids it being done for an improper reason. … Presidents are no exception.”

If the president asserts the kind of unchecked power contemplated in these letters, Congress must act. If it doesn’t, then its passive stance would neuter the constitutional balance of powers: If the coequal Article I branch of government — Congress — signals that it won’t act to restrain the Article II branch — the executive — when that branch oversteps, then the most important safeguards carefully put in place by the Constitution’s Framers could well be rendered useless, and the president’s power would, indeed, more closely resemble those of a king.