Glenn Harlan Reynolds

Opinion columnist

The “Cheesehead Stasi.” That’s what Twitter humorist IowaHawk called a long-running and politicized investigation organized by Democratic politicians in Wisconsin, targeting supporters of Republican Gov. Scott Walker. The mechanism for this investigation was an allegedly nonpolitical, but in fact entirely partisan, “Government Accountability Board.”

In the course of its secretive “John Doe” investigation, the GAB hoovered up millions of personal emails from Republican donors and supporters, and even raided people’s homes, while forbidding them to talk about it:

“I was told to shut up and sit down. The officers rummaged through drawers, cabinets and closets. Their aggressive assault on my home seemed more appropriate for a dangerous criminal, not a longtime public servant with no criminal history,” Archer wrote in a June 30, 2015, Wall Street Journal op-ed. The column was published a day before she filed her civil rights lawsuit. When the agents finally left her home, Archer said she took inventory of the damage. She found drawers and closets ransacked, her “deceased mother’s belongings were strewn across the floor.” Like so many other targets of the secret John Doe investigation, Archer was forced to watch her neighbors watch her — the star of a very public search-and-seizure operation. . . . And like her fellow targets, she was told she could say nothing publicly about being a target of Chisholm’s probe. Doing so could have landed her in jail and hit with hefty fines. The secret investigations come with strict gag orders."

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Now an investigation by Wisconsin Attorney General Brad Schimel on behalf of the overseeing court has spelled out a long list of misdeeds by the investigators, and has called for punishments including contempt-of-court holdings and possible disbarment. And the stuff that it has uncovered is pretty awful.

In short, it was a partisan witch hunt masquerading as an inquiry into campaign irregularities. And confidential information gathered during that investigation was deliberately leaked in an effort (unsuccessful) to influence a pending United States Supreme Court decision.

The prosecutors felt justified in these actions because they had already made up their minds about their targets’ guilt. As the report says, “After reviewing the emails exchanged between the attorneys at GAB, it is apparent that GAB attorneys had prejudged the guilt of Governor Walker, Wisconsin Republicans, and related organizations that they were investigating and this dramatically influenced their ability to give competent legal advice. GAB attorneys did not act in a detached and professional manner. The most reasonable inference is that they were on a mission to bring down the Walker campaign and the Governor himself.”

The investigation continued despite its failure to find anything like the sort of violations it was ostensibly intended to investigate. It continued despite court orders to stop. And prosecutors retained evidence (including medical and other records about Republican officials and donors, kept in a file labeled “opposition research”) even after being ordered by the Wisconsin Supreme Court to turn all the information over. It was a lawless exercise of prosecutorial power, for political ends.

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Wisconsin Democrats took Scott Walker’s victory very hard. They tried to recall him, and failed. And they tried to undermine his term in office through the abuse of legal institutions. Now some of them will face professional discipline, and judicial punishment, as a result. (Criminal charges would be appropriate, except that, as the Attorney General’s report notes, record-keeping was — conveniently — poor enough that it’s hard to be sure exactly who did what.)

Given the vast powers with which prosecutors are entrusted, it’s easy for an investigation to get out of hand, especially when the investigators are a partisan bunch lacking in political diversity, and start out with the certainty, shored up by political resentment, that their targets must be guilty of something. But these abuses can ultimately turn back on the abusers.

It’s too early to say, as one account does, that the Wisconsin debacle prefigured the ongoing Robert Mueller investigation into Trump’s campaign, though there are certainly similarities between the attitudes of “The Resistance” in Washington and the Wisconsin establishment’s response to Walker. Writing in The Washington Post last week, Ed Rogers wrote that, though he’d supported Mueller in the past, Mueller needed to get a handle on the overwhelming partisan slant of his prosecutors or he’d be discredited.

It’s good advice. Mueller and his investigators should take care not to get wrapped up in partisan politics while conducting a criminal investigation. Because that seldom ends well.

Glenn Harlan Reynolds, a University of Tennessee law professor and the author of The New School: How the Information Age Will Save American Education from Itself, is a member of USA TODAY's Board of Contributors. Follow him on Twitter: @instapundit.