Comey is toast. The report issued Thursday by the inspector general of the Department of Justice fried the former FBI director a light golden brown. There is no coming back from this, no matter what he or anyone else says.

As the report makes clear, Comey’s actions were insubordinate, against clear DOJ policy, and often motivated by self-interest. He actively manipulated his superiors and brought the FBI into disrepute. While he may not be as bad as my fellow columnist, Mr. Carr, says, he is pretty bad, and he would do well just to slink into obscurity and trouble us no more.

What also died on Thursday was the obstruction case — if there ever was one — against President Trump. As readers may recall, this all started when Comey was fired and the left collectively raised a hue and cry alleging that the firing was simply an excuse to impede the FBI investigation of the Russian impact on the election. According to this view, Comey was the last bastion of integrity and President Trump’s asserted justifications for the termination were a sham.

And now, as a few have already suggested, that’s all gone. According to the report, not only was the firing of Comey appropriate, it was really necessary. So where does that leave the Mueller investigation?

Suppose they accuse Mr. Trump of firing Comey for bad reasons. Trump’s lawyers drop the report — prepared by an Obama-administration appointee — on the bench or in front of the jury. “Here,” they say, “is documented proof that the firing was entirely justified as determined by the DOJ itself and documented by this objective investigation. If the president can’t fire this guy, where is the republic now?”

Any reasonable lawyer would recognize that the prosecutors just lose in that situation. Even if they still believe that Mr. Trump had evil in his heart, they are doomed in court. And for a prosecutor, what happens in court is what matters. If there is no reasonable expectation of getting a conviction, a prosecutor should not indict. That is DOJ policy, too.

As I used to tell clients, trials are not about what is true, they are about what you can prove in court. Any criminal obstruction case is now unprovable. It is time to move on.