Maricopa County Sheriff Joe Arpaio has been a controversial figure in the immigration politics debate for some time now, flaunting his hard-line approach to immigration enforcement in a way that rallies fellow hard-liners and engenders his reputation as arch-demon on the left.

Now, the Obama administration is suing him for failing to cooperate with an investigation into his law-enforcement practices--an issue that lies at the heart of the Justice Department's lawsuit against Arizona's SB 1070 law.

The Justice Dept. announced yesterday that Arpaio was refusing to provide documents and that it was suing him.

This is a showdown that, I suspect, many people will want to see. Possibly on pay-per-view. But this lawsuit isn't actually about immigration policies or how Arpaio runs his law enforcement operations. It's about cooperation with the department's investigation. Arpaio seems to be the one who has publicized the department's investigation by refusing to cooperate.

At The Washington Examiner, Byron York doesn't think the probe will go anywhere, and that this whole episode could end in embarrassment for Holder:

Despite the splash of attention from the newest lawsuit, the Justice Department's investigation of Arpaio could end badly for Holder. When the Department first informed Arpaio that a probe was under way, back in March 2009, it sent a letter saying the investigation would focus on "alleged patterns or practices of discriminatory police practices and unconstitutional searches and seizures." But now we learn that just six months before that, in September 2008, the Immigration and Customs Enforcement agency, known as ICE, did its own investigation of Arpaio's office -- and gave it a clean bill of health. Arpaio's lawyers recently got a copy of the ICE report through the Freedom of Information Act.

The investigation of Arpaio may carry more political significance than the Justice Dept. lawsuit against Arizona. Opponents of SB 1070 typically cite police harassment and discrimination as the reasons they think the law is wrong, but the Justice Dept.'s lawsuit against Arizona doesn't really confront those issues. The case against SB 1070 rests on the Constitution's Supremacy Clause and a state's right to make immigration laws. (See a summary of the Justice Dept.'s SB 1070 case here.)

The investigation of Arpaio, however, is a civil-rights investigation. Meaning that, if the Justice Dept. finds him to have violated people's civil rights and decides to sue him over that, we'll get to see Holder's Justice Dept. fight the civil rights battle in a courtroom, and the real political issue will be dealt with.

The SB 1070 suit won't afford us such a showdown, and it's a showdown everyone would want to see. Critics of the SB 1070 lawsuit are rooting for Holder to fail, and they see his department's move as an extension of the Obama administration's liberal immigration stance and its supposed penchant for federal authority. The left sees Arpaio as a symbol of civil rights violations and all that's wrong with the hard line on immigration.

Of course, the department may not find it has a case, and the drama may well just dissipate. Which wouldn't be nearly as exciting.

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