What I remember most about Joe Arpaio’s jail is how easy it was to get in. We were interviewing people from the Hispanic community in Phoenix under siege from Arpaio’s cops. This was when they were routinely scooping migrants off the streets and – sometimes even when all their papers were in order – dumping them into immigration detention jails. I assumed the BBC would have trouble getting access to such a controversial institution, but within an hour of asking we were through the doors.

The jail was a tent camp: olive-green military canvas with the sides pulled up, dating from the Korean war. The prisoners – women were in a separate compound – all wore black and white striped overalls and, famously, bright pink underwear. Arpaio himself would later sign for each of my team a poster showing a brutish-looking prisoner wearing the pink underwear: it was designed, like the rest of the place, to humiliate and increase the mental torture.

The physical unpleasantness was plain to see. Our car dashboard told us the outside temperature was 114F (45.5C). The prisoners lay slumped, listless in the suffocating heat. The guard escorting us said: “Everything is done as cheap as possible. They get two meals a day: bologna [sausage] and cheap white bread. We, the guards, drink only out-of-date Gatorade for hydration.” And he proudly showed us the date on the bottle he was swigging from. At the slightest unauthorised physical movement – such as shading your head from the sun under a pink towel on the way to the bathroom – the guard would bark some insulting instruction at the offender until they froze.

We did not see the solitary cells or the all-female chain gang – though Arpaio would have showed us if he’d had the time. The entire purpose of the hell-hole he built, in steady defiance of federal laws and regulations, was to deter migration.

The jail, relentless police raids and stops of people who looked Hispanic, and the tirade of contempt and racial stereotypes that spewed out of Arpaio’s mouth when I interviewed him, were all designed to make life as difficult as possible for the migrant communities of Arizona. But the circus of cruelty was only the pretext for a bigger signal. Arpaio’s actions, over 20 years as sheriff of Maricopa County, Arizona, were designed to prove that the American far-right can defy the constitution and the federal government with impunity. That is what President Trump really sanctioned when he pardoned Arpaio last week: open defiance of the law.

Trump adviser Roger Stone, who was instrumental in getting Arpaio off the hook, is hard at work on a deal to pardon Cliven Bundy, whose far-right militia confronted government forces in Nevada in 2014 and who is currently in jail. As you ponder the significance of a presidential confidant colluding with an armed militia leader who believes violence against the government is justified, ponder also Stone’s prediction that an impeachment attempt on Trump would be met with “a spasm of violence in this country, an insurrection like you’ve never seen”.

The report I made from Arpaio’s jail changed nothing. Even a Pulitzer prize-winning investigation into the high cost of Arpaio’s failure to fight actual crime changed nothing. Arpaio was filed – like Trump himself – under the category “weird stuff at the edges of American life”. Now, like the army of zombies in Game of Thrones, all the sick-brained oddities of the American right are over the wall. Stone, Trump, Arpaio and Steve Bannon range across US civil society with impunity, giving the sly nod to fascists, Klansmen, violent misogynist groups and armed militias., designating the media as enemies of the people.

It would be terrifiying if these were our enemies, but the US is supposed to be our ally: the self-advertised land of the free, arsenal of democracy and other now-meaningless aggrandisements.

When Trump’s defence chief James Mattis told troops in Jordan last week they had to “hold the line” until the US recovered its ability to inspire the world, you could hear the confidence draining out of traditional Republicanism. Trump is now so heavily at odds with large sections of the corporate elite that, in any normal liberal democracy, they would welcome the first chance to oust him.

But – and we must force ourselves to face this – the US is becoming an abnormal democracy. Its old, stone institutions look the same, but the rule of law and the impartiality of justice are evaporating. The forces defending US democracy – the broadsheet newspapers, the billionaire-funded foundations and NGOs, the unions, the protest groups and, above all, the Democrats – have never faced a threat like this. There is a strong atmosphere of denial and complacency.

Stone’s warning was a signal to Republican senators who might be tempted to back an impeachment bid. “A politician that votes for it would be endangering their own life,” he said. It was also an indirect warning to those corporate chiefs who quit Trump’s advisory committees in the wake of Charlottesville. Soon, they too will join the list of enemies to be vilified and threatened.

It’s not yet 20 years since the US right proclaimed the unipolarity of the world: America reigned supreme and could shape the system, imposing democracy and order on emerging markets. What a joke that seems now.

The US cannot even impose democracy on itself. All who understand geopolitics must fear the consequences. The norms of behaviour set in Arizona – the threats against political opponents, the raids against rival law enforcement agencies, the harassment of the press – are becoming norms in Washington. In turn, Trump’s resort to arbitrary rule is a signal to every kleptocrat and police state in the world: it’s all right, keep going.

All we can do is to go on restating the principles of law and freedom. And hope that, if we have to fight for them here in Europe, we will do it earlier and more effectively than the beleaguered progressives of the US.