Whether Special Counsel John Durham’s inquiry ends with a bang or a whimper will depend, it appears, on how the upcoming trial goes for a man accused of lying to the FBI. If that sounds anticlimactic, it’s because Mr. Durham’s previous attempt to try someone for deceiving G-men fizzled when a Clinton campaign lawyer, Michael Sussman, was acquitted. Yet the real target of this upcoming trial could prove to be the FBI itself.

Mr. Durham’s remit, set by Attorney General Barr in October 2020, was to investigate any federal wrongdoing, including “intelligence, counter-intelligence, or law-enforcement activities,” directed at the 2016 presidential campaigns. The probe was catnip for President Trump and his supporters, who welcomed the chance to unveil the work of the Deep State, and even the Clinton campaign, in the effort to tie Mr. Trump to Russia. 

Yet Mr. Durham’s probe has proven a disappointment on this head. Our Conrad Black decries it as “a mountain of anticipation that ultimately and with the utmost difficulty produced the long delayed, still-born mouse of a single prosecution,” that of Mr. Sussman. Lord Black writes Mr. Durham is moving at “the pace of a determined snail towards the trial of his second indictee.” Even CNN reports it is “falling short of expectations.”

After all, Mr. Durham “has not charged any government officials with any crime,” CNN observes. Even if he wanted to, “the five-year time limit for federal investigators to bring most criminal charges” would appear to have passed. Plus, too, the term of Mr. Durham’s grand jury has expired. So is he going to pull any rabbits out of his hat at the upcoming trial in federal court of the Russian national accused of lying to the FBI, Igor Danchenko?

An ex-federal prosecutor, Andrew McCarthy, thinks so. He notes Mr. Danchenko is “the principal source for the discredited Steele dossier” and reckons the trial “should be grabbing our attention.” The dossier, a farrago of insinuations designed to smear Mr. Trump as a pawn of Putin, was “one of the great dirty tricks in modern political history,” Mr. McCarthy contends. And it was, he says, “a Clinton campaign production.”

The leak of the dossier in January 2017 cast a shadow over Mr. Trump’s presidency. While he was eventually vindicated by the failure of the Mueller investigation to find any wrongdoing, the accusations were at least a distraction and at worst a partisan drive to derail his administration. Yet the dossier was also used by the FBI as the basis — along with information from Mr. Danchenko — for launching further probes against Mr. Trump.

On the face of it, Mr. Danchenko lying to the FBI may not seem all that dire. When he was indicted in November, our Ira Stoll observed that the law he is charged with breaking “is one of the most frequently used, and problematic, pieces of criminal law on the books.” Mr. Stoll reports that this law had “been on my radar screen since 2004, when a New York Sun editorial noted its use against Martha Stewart.” We’re with him.

Yet the fact that Mr. Danchenko was unveiled as a paid FBI informant, as a court filing disclosed last week, casts his alleged lies in a different light, Mr. McCarthy writes. The untruths Mr. Danchenko told the FBI “should have been easy for the nation’s flagship federal investigative agency to run down,” he writes. “Yet they kept him on board, kept paying him.” This suggests Mr. Durham is more interested in the FBI than Mr. Danchenko here.

After all, Mr. Danchenko’s falsehoods were blatant, Mr. Durham contends: he “could not keep his lies straight.” In one instance, Mr. Danchenko even furnished the FBI with information that disproved his own previous statements. He “slipped up by providing the FBI with an email that contradicted his own prior lies,” as Mr. Durham puts it. Yet “the FBI apparently did not identify or address these inconsistencies.”

This matters because Mr. Danchenko’s claims were used to justify more investigations against Mr. Trump. Had the FBI been aware of those lies, Mr. Durham writes, “the FBI and DOJ would have been under an affirmative obligation to inform” the Foreign Intelligence Surveillance Court “about information that would have undermined the statements it had made” in previous applications. One might call that accusation — well, explosive.