The distinction may seem minor, but it’s significant. To find lack of candor in an internal probe, investigators have only to decide among themselves that an official dissembled or didn’t give a complete answer. In a prosecution for lying to investigators, prosecutors must convince a jury beyond a reasonable doubt not only that the defendant lied, but also that the defendant knew he was lying. This is a much higher bar to clear.

For this reason, it’s surprising that the Justice Department may be pressing forward with charges against Mr. McCabe. In fact, the case appears to be sufficiently contentious that, according to The Times, at least one prosecutor has left the department over it, and one key witness has already given grand jury testimony helpful to Mr. McCabe’s defense.

Prosecutors may yet decide not to bring charges. If they do charge him, perhaps there is some damning additional evidence against Mr. McCabe beyond what’s on the public record. But on the basis of publicly available information alone, any prosecution would be, to say the least, puzzling — and would take place in the president’s long shadow.

If the case does go to trial, Mr. McCabe’s defense team would have the chance to request information regarding what role Mr. Trump and the White House might have played in the decision to seek an indictment. That material might be damning, or it might show nothing at all. Either way, though, it is impossible to completely wipe away the doubt about the integrity of the case against Mr. McCabe. Even if the president said nothing in private to indicate he was pushing for his perceived enemy’s prosecution, he has said plenty in public; even if he has given no direct instructions, he has made clear that he expects the Justice Department to act as his fixer.

In seeking to leverage the power of the state against his enemies, the president appears to be acting out what he believes his enemies have already done to him — he has, after all, blamed Mr. McCabe in part for the “Russia hoax.” This is a vicious cycle. Even if Mr. Trump’s actions toward Mr. McCabe did not go beyond what he’s said in public, he’s made it impossible for even his political opponents to trust the institutions that he believed from the start were untrustworthy. The poison is already in the water.