President Trump pardoned former Maricopa County, Ariz., sheriff Joe Arpaio Aug. 25. Here's what you need to know. (Patrick Martin,Victoria Walker/The Washington Post)

On Friday night, as Hurricane Harvey was bearing down on the Texas coast, President Trump pardoned Joe Arpiao. The former Arizona sheriff had been convicted of criminal contempt for ignoring a judge's orders to stop detaining people simply because he suspected them of being undocumented immigrants. (Over his decade-long career, his Maricopa County department was also accused of abusing prisoners, subjecting inmates to inhumane punishment and of ignoring other important crimes to track and expel immigrants.)

It's a controversial decision, one that Trump critics labeled as an example of the president's illiberal, rule-of-law violating, authoritarian impulses.

New York magazine called it, “Donald Trump’s gravest abuse of power yet.” An op-ed contributor for the New York Times said that Trump's decision put him in “uncharted waters,” writing " if the president can employ the pardon power to circumvent constitutional protections of liberty, there is very little left of the constitutional checks on presidential power.” Bob Bauer, a former White House counsel in the Obama administration, suggested on Lawfare that  the decision showed a clear disregard for the rule of law.

Even before Trump granted the pardon, Noah Feldman, a law professor at Harvard, argued that such a move “would express presidential contempt for the Constitution.”

How valid are these concerns? We surveyed a handful of professors who study authoritarianism in other countries on what they see in Trump's decision, and whether it makes them nervous:

Ruth Ben-Ghiat, a New York University professor who studies authoritarian rulers, propaganda and fascism and its memory:

“In situations where democracies become right-wing regimes, the leader usually relies on paramilitary or other extremist forces to get into office or consolidate power once he's there. He has to dance the line between expelling them and using them. Trump's expulsion of Stephen Bannon and Seb Gorka, coming together with his open support of white nationalism and now his pardon of Joe Arpaio, shows this dynamic well.

“If the leader does not explicitly renounce the violent rhetoric and actions of extremists, they will have done their damage even if he later purges them. The result is a new culture of violence in the country, which the other armed and security forces of society must adapt to.”

Tom Pepinsky, who studies interaction of political and economic systems in emerging market economies at Cornell University: 

“Authoritarians generally don't allow their officials to be convicted of anything in the first place. So it's a sign of how much the president is working against the system that produces outcomes that he doesn't like one bit.

“Now, I think it is meaningful that Arpaio is a law enforcement official, but that's because it reveals the hollowness of 'law and order' presidency. What I'd really find more troubling is if he starts pardoning your everyday police officers who are convicted of the abuse of power or other violent crimes.”

Cas Mudde, a University of Georgia professor who studies political extremism and populism in Europe: 

“In real autocracies, dictators don't have to pardon people, because they would never get sentenced! In other words, this is, at best, a sign of an illiberal democrat caught up in a liberal democratic system.

“The most contentious, and remarkable, part of the pardon is not the person pardoned — 'Sheriff' Arpaio is a hero to the Trump base and therefore makes a perfect candidate (it's often heroes of the base or donors of the party/president) — but the timing of the pardoning. First of all, it is very early in the presidency and, second, it is before Arpaio has been sentenced. I think the latter is a clear reflection of President Trump's  complete disregard for the rule of law. He believes in the rule of power, in part because he has experienced throughout his lifetime that this is how U.S. justice works. However, the timing is probably, as several others have also noted, more linked to the issue that predominates President Trump's mind: the Russia investigation. There are several key people in his former entourage who are at the point of caving to pressure to working with the [Robert S.] Mueller investigation. Trump has shown them that they have nothing to fear, because he can and will pardon them, irrespective of the circumstances. This, of course, is a fundamentally undemocratic position, but not so much informed by ideology but by naked self-interest.”

Sherri Berman, a European history professor at Barnard

“Pardoning itself is not a particularly authoritarian policy, as you know. All presidents have this right, but how they use it often signals their priorities or at least personal preferences.  (President Barack Obama, for example, made a big show of pardoning nonviolent drug offenders.) So I would treat Arpaio's pardoning as a political and in particular a signaling move on Trump's part — and a smart one. I think Trump has been very good at this — he hasn't been able to get many things through Congress, but he has 'compensated' with exec orders and symbolic politics that have, for the most part, kept his base attached.”