THE most troubling interpretation of the executive order that Donald Trump signed on January 27th, temporarily banning visitors from seven mainly Muslim countries, is not that the president means to honour his campaign promises. It is that he will find ways to do so even where what he promised—in this case, to keep Muslims out of America—is illegal. “When he first announced it, he said ‘Muslim ban’,” explained Rudy Giuliani, a former would-be Trump attorney-general. “He called me up, he said, ‘Put a commission together, show me the right way to do it legally’.”

Even if Mr Trump can resist the urge to lock up Hillary Clinton and reinstitute torture, which he also promised to do on the trail, he is already testing the boundaries of presidential propriety and power. The potential conflicts of interests in his administration are an obvious example: Mr Trump is the first president since Richard Nixon not to sell or place in blind trust his business, including a hotel division that has announced plans to triple its American properties since his inauguration.

All this is worrying in itself. Making matters worse, however, is the sorry state of America’s system of checks and balances, a web of mutually compromising powers woven, in fear of tyrants, around the presidency, Congress and judiciary. “We’re not quite at code blue,” says Norm Ornstein of the American Enterprise Institute. “But we are definitely in the emergency room and heading towards the intensive-care unit.”

This might sound surprising. In his first 11 days as president, 42 law suits were fired at Mr Trump or his administration. Massachusetts, New York, Virginia and Washington challenged the immigration order. But the courts alone will not constrain Mr Trump. Courts can issue stays to pause executive actions. But it could take over a year for the states’ challenge to reach the Supreme Court. By then Mr Trump could have changed America’s immigration system so much that the judges’ verdict would be largely irrelevant.

The legal firepower recently accrued by the presidency has also made the judges’ task harder. The job of White House counsel was created to provide the president with sound legal advice; it has ballooned into a battery of lawyers—almost 50 under Barack Obama—whose task is to find legal cover for whatever the president wants to do. The evolution of the proposed Muslim ban into a bar on visitors from some countries was consistent with such machinations. And this is indicative of a wider power grab by the executive, gaining strength for decades, which accelerated under Mr Trump’s immediate predecessors.

In matters of war, foreign policy and civil liberties, for example, George W. Bush and Barack Obama claimed vast power. And neither the courts nor Congress, even when hostile to the president, seemed able to stop them. If Mr Trump assumes the right to order the execution of American citizens suspected of terrorism or to try someone on the basis of evidence that the state will not divulge, he will merely be following the example of his predecessors.

It was largely on the basis of this power grab that Bruce Ackerman, a legal scholar, predicted in 2010 that the president would be changed “from an 18th-century notable to a 19th-century party magnate to a 20th-century tribune to a 21st-century demagogue.” The current situation may be worse than he envisaged in “The Decline and Fall of the American Republic”, due to the eagerness of the Republican-controlled Congress to pander to Mr Trump, weakening the main check on the presidency.

A month before the election, after a video surfaced in which he boasted of his ability to maul women, 16 Republican senators and 28 Republican members of the House of Representatives said they no longer supported him. Yet Mr Trump’s unruly first fortnight in power, including much evidence that the White House has become, as Mr Ackerman foresaw, a “platform for charismatic extremism and bureaucratic lawlessness”, has drawn few whispers of dissent from Republican congressmen. A few senators, led by Ben Sasse of Nebraska, John McCain of Arizona and Lindsey Graham of South Carolina, have ventured criticism, especially over warnings that Mr Trump will lift sanctions on Russia. Yet at the Republican retreat in Philadelphia on January 26th, dominated by talk of health-care reform, tax cuts and deregulation, the cheers for the president were full-throated. “I cheered him myself,” said Mr McCain. “I want him to succeed, I believe he is commander-in-chief, so, where we disagree, I can’t just play whack-a-mole.”

The reasons for the growth of tribalism in American politics over the past half century—which include the culture wars, introduction of primaries and success of Newt Gingrich, a former Speaker of the House and now Trump henchman in transforming what had been a consensus-prizing assembly into a parliamentary bear-pit—are so familiar that it is easy to lose sight of how dynamic a process this is. Partisanship does not simply imply deadlock, of the kind that bedevilled Mr Obama. It is steadily eroding the norms that enshrine the cautiously collaborative spirit of the American system, in which much of its defence against authoritarianism resides.

Thus, for example, the parcel of House rules and conventions known as the Regular Order which was designed to ensure all members, including those of the minority party, got a fair crack at amending and debating bills; it was trashed by one of Mr Gingrich’s successors, Dennis Hastert, who is now in jail for molesting children. Similarly, the filibuster, which was conceived as an emergency device to prevent the minority having egregious legislation and government appointments imposed on it. Once rarely used, it was employed by Democrats to block five Bush appointees a year; it was used by Republicans to block 16 Obama appointees a year, driving the then Democratic leader in the Senate, Harry Reid, to abolish its use in blocking cabinet appointments. If the Democrats try to block Neil Gorsuch, whom Mr Trump nominated for the vacant Supreme Court judgeship on January 31st, the Republicans will probably abolish its use in that case also. And another important check on the tyranny of the majority party will be lost.

It is striking that such great changes have not caused more disquiet. That probably reflects the fact that while the parties drifted apart, America continued to elect presidents who were more centrist than their parties. Mr Bush’s and Mr Obama’s agendas were in some ways more similar to each other than Mr Trump’s is to either. Moreover both former presidents honoured the constitutional system; when their edicts were checked, they retreated. That is not an attitude Mr Trump’s rhetoric suggests he shares.

“Can the system that has put a demagogue in the White House now hold him to account?” asks Mr Ackerman. “We don’t know. But I can say that over the past half century its capacity to restrain has been dramatically reduced.”