To seat a 12-person jury, Judge Robert L. Deschamps III of Missoula County District Court had called a passel of Montanans to serve, and 27 had arrived at court on Dec. 16. So far, so good.

But after the charges were read, one of the jurors raised a hand.

“She said, ‘I’ve got a real problem with these marijuana cases,’ ” Judge Deschamps recalled on Wednesday. “And after she got through, a couple more raised their hands.” All told, five jurors raised questions about marijuana prosecution.

And so it was that Mr. Cornell soon became the lucky recipient of a case of almost-a-jury nullification, as prosecutors soon found themselves cutting a deal to dismiss the misdemeanor possession charge out of fear that they would not be able to find 12 jurors in this marijuana-friendly state to convict.