Noah Feldman at Bloomberg says pardoning Arpaio would be an attack on the judiciary itself.

Arpaio was convicted this July by Judge Susan Bolton of willfully and intentionally violating an order issued to him in 2011 by a different federal judge, G. Murray Snow.

The order arose out of a civil suit against Arpaio brought by the American Civil Liberties Union, accusing him of violating the law by detaining undocumented immigrants simply for lacking legal status.

Snow issued a preliminary injunction that ordered Arpaio to stop running so-called saturation patrols — police sweeps that essentially stopped people who looked Latino and detained those who were deemed undocumented. The basic idea was that the profiling, warrantless stops and detention were unconstitutional.

Yet despite the federal court’s order, Arpaio kept running the unlawful patrols for at least 18 months, and publicly acknowledged as much.

We don’t want law enforcement people doing that, any more than we want the military doing that.

Judge Bolton convicted Arpaio of criminal contempt. She found he had “willfully violated” the federal court’s order “by failing to do anything to ensure his subordinates’ compliance and by directing them to continue to detain persons for whom no criminal charges could be filed.” And she held that Arpaio had “announced to the world and to his subordinates that he was going to continue business as usual no matter who said otherwise.”

This is the crime that Trump is suggesting he might pardon: willful defiance of a federal judge’s lawful order to enforce the Constitution.

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Such a pardon would reflect outright contempt for the judiciary, which convicted Arpaio for his resistance to its authority. Trump has questioned judges’ motives and decisions, but this would be a further, more radical step in his attack on the independent constitutional authority of Article III judges.

An Arpaio pardon would express presidential contempt for the Constitution. Arpaio didn’t just violate a law passed by Congress. His actions defied the Constitution itself, the bedrock of the entire system of government. For Trump to say that this violation is excusable would threaten the very structure on which is right to pardon is based.

Fundamentally, pardoning Arpaio would also undermine the rule of law itself.

The only way the legal system can operate is if law enforcement officials do what the courts tell them. Judges don’t carry guns or enforce their own orders. That’s the job of law enforcement.

In the end, the only legally binding check on law enforcement is the authority of the judiciary to say what the law is — and be listened to by the cops on the streets.

And we need to have a legally binding check on law enforcement. They’re heavily armed.

The Constitution isn’t perfect. It offers only one remedy for a president who abuses the pardon power to break the system itself. That remedy is impeachment.

James Madison noted at the Virginia ratifying convention that abuse of the pardon power could be grounds for impeachment. He was correct then — and it’s still true now.

But that of course does not mean it will happen.