By the fall of 2017, it was clear that special counsel Robert Mueller, as a former director of the Federal Bureau of Investigation, was too conflicted to take a detached look at a Russia-collusion story that had become more about FBI malfeasance than about Donald Trump. The evidence of that bias now stares at us through 448 pages of his report.

President Trump has every right to feel liberated. What the report shows is that he endured a special-counsel probe that was relentlessly, at times farcically, obsessed with taking...