“I WAS surprised by the statement,” Justice Department Inspector General Michael Horowitz testified Wednesday before the Senate Judiciary Committee. We could think of a few more ways he could have felt — frustrated, dismayed, outraged — at the spin that senior Justice Department officials put on his long-awaited report. The review of the department’s investigation of President Trump’s 2016 campaign and Russian election meddling found that the probe was properly launched and that there was no indication of political bias. It also found that the FBI breached protocol in the secretive Foreign Intelligence Surveillance Act (FISA) process. That deserves further discussion — but not, as Attorney General William P. Barr has done, to dignify the president’s “deep state” conspiracy theories.

Almost simultaneously with the report’s release Monday, Mr. Barr dismissed and minimized Mr. Horowitz’s findings — or, at least, the ones that failed to paint the FBI as a rogue agency nursing an anti-Trump agenda. “The FBI launched an intrusive investigation of a U.S. presidential campaign on the thinnest of suspicions that, in my view, were insufficient to justify the steps taken,” he said. The next day he raised “the possibility that there was bad faith.”

U.S. Attorney John Durham, whom Mr. Barr handpicked to conduct yet another investigation of the Russia probe, piled on, saying that “we do not agree with some of the report’s conclusions as to predication and how the FBI case was opened” and implied that he had uncovered new evidence that might shift the picture. This was the statement that surprised Mr. Horowitz. Its innuendo left unanswered whether Mr. Durham has turned up something new.

The responses suggest a warped view of what is significant. The FBI opened its investigation into the Trump campaign after receiving a credible report that a Trump aide had said the Russians had obtained Hillary Clinton’s emails, just as federal officials were seeing Russian attempts to interfere with the 2016 presidential election. Mr. Barr on Tuesday called these alarming facts a “flimsy” basis on which to launch an investigation. In reality, the FBI had an obligation to determine, on the fly and in unprecedented circumstances, whether there was collusion.

The inspector general explained Wednesday that Mr. Durham told him a preliminary, rather than full, investigation was warranted, even though, in either case, the FBI could have taken investigative steps similar to those it pursued. If this is the issue, it is a flimsy one on which to hang a public rebuke of Mr. Horowitz, particularly when doing so plays into Mr. Trump’s raging about the “scum” at the FBI who dared investigate him.

In fact, the inspector general’s important findings were not limited to the question of whether an investigation was warranted or inflected with political bias. He also found that the Justice Department committed serious lapses in seeking and renewing a FISA warrant against Trump campaign adviser Carter Page. The FISA court’s secret nature and substantial powers have long made many Americans queasy — even after reforms Congress imposed in the 2015 USA Freedom Act. In another time, the inspector general’s findings would be fodder for weeks or months of debate on revising the federal government’s surveillance practices. But Mr. Trump’s obsession with conspiracy theories diverts attention from real problems.

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