For more than a year and a half, everyone from House Oversight Committee chairman Darrell Issa to right-wing provocateurs on Fox News have been lobbing fiery accusations about Operation Fast and Furious, including that it was a plot conceived by the White House for a variety of nefarious purposes.

Fast and Furious, you will remember, was the name of an investigation run by ATF agents and federal prosecutors in Arizona that allowed thousands of guns to be sold to operatives of Mexican drug gangs who then smuggled them across the border for use in the drug war. The operation was exposed after a U.S. border agent, Brian Terry, was killed and two guns that ATF and prosecutors had allowed to “walk” as part of Fast and Furious turned up at the scene of the crime.

You will also remember that Republicans worked themselves into a rabid fever on the subject. One expects a certain amount of irresponsible and baseless accusation from far right commentators, but it’s worth remarking on just how outlandish the accusations were. Ann Coulter declared that the operation was run by Holder for the White House with the intention of killing American law enforcement officials for the purpose of advancing gun control:

Until someone can tell us otherwise, there is only one explanation for why President Obama’s Bureau of Alcohol, Tobacco, Firearms and Explosives gave thousands of guns to Mexican drug dealers: It put guns in their hands to strengthen liberals’ argument for gun control… Innocent people dying was the objective of Fast and Furious, not collateral damage.

And after the Obama administration cited executive privilege and refused to provide documents to Congress (documents later made available to Horowitz for his investigation), Michelle Malkin said Obama himself was involved:

The maneuver that they undertook yesterday just underscores something that some of us have been emphasizing since day one of this scandal over the last year and a half – and that is that Obama is at the center of it.

That kind of talk may be standard operating procedure for those people who make a living exploiting the basest fears of people on either end of the political spectrum. But House Oversight and Government Reform Committee Chairman Darrell Issa, R-Calif., himself got in on the action last summer, alleging that Obama or his senior advisers “were involved in managing Fast and Furious and the fallout from it.”

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Yesterday, the Department of Justice Inspector General, Michael Horowitz, a former federal prosecutor in the Southern District of New York, released his long awaited report on the scandal, meticulously detailing responsibility for the operation and the cause of false statements made to Congressional investigators by members of the administration, including Attorney General Eric Holder.

Horowitz managed to impress the House GOP in briefings over the past week, and the report itself was met with support from all quarters. GOP Rep. Jason Chaffetz of Utah complimented Horowitz at a House Oversight hearing Thursday for his “tenacity” and his “wonderful report.” Issa himself called Horowitz and his report “courageous.”

What none on the right are admitting is that Horowitz’s report systematically reveals how irresponsible and speculative the accusations from their side have been. The report criticizes Holder’s Criminal Division chief Lanny Breuer for failing to inform Holder or his deputy that “gun walking” had taken place in the Bush administration in another case in Arizona called “Wide Receiver”. But the report shows that Breuer knew nothing about gun walking in Fast and Furious, and that therefore the scandal existed three levels below Holder (let alone the White House). Says the report:

[Breuer] did not learn about Operation Fast and Furious and the allegations about the use of improper investigative tactics in that investigation until after Sen. Grassley’s January 27 letter.

And:

Breuer did not supervise Operation Fast and Furious and did not authorize any activities in the investigation… Breuer had no role in authorizing [F&F] wiretap applications…

As for the source of the false statements to Congress, Horowitz finds they were the result of inaccurate reassurances given to Breuer’s deputy Jason Weinstein, by the U.S. attorney in Arizona, Dennis Burke. As Congressional inquiry began into the matter in January 2011, the lead prosecutor on Fast and Furious, Emory Hurley, informed Burke that guns found at the Terry murder site had been part of Fast and Furious. Burke, however, told Weinstein that they were not. Weinstein, and the rest of the Justice department, ran with that assurance in response to Congressional questions. Only later did the Justice Department’s central office discover they were wrong.

Horowitz does dispense with one unsubstantiated claim from the left side of the aisle. Some Democrats have said Fast and Furious shows lax gun laws are to blame for the weapons trafficking that contributed to agent Terry’s death. Horowitz finds that prosecutor Hurley and ATF agents in the case did believe they didn’t have sufficient probable cause to seize weapons during Fast and Furious, and Horowitz rejects their “narrow view” of “the quality and quantity of evidence that was necessary to take enforcement action.”

But ultimately Horowitz says it was not the legal view that prevented ATF or U.S. prosecutors from interdicting the guns in Fast and Furious, but a tactical and strategic decision to let the guns walk in order to pursue higher-ups in the gun-running, drug-smuggling and money laundering operation they were investigating.

Horowitz destroys the conspiracy theories on both sides of the aisle over 471-pages, but it’s the right wing screamers who come out looking worst. Horowitz shows definitively that the Arizona ATF agents and prosecutors in the U.S. Attorney’s office there were responsible for the operation, not the White House or the Justice Department in Washington and that the primary source of the inaccurate testimony given to Congress was the U.S. Attorney for Arizona, Dennis Burke.