But he feels his message must be getting out, or the government would not have brought charges against him.

“If I weren’t having any effect, would they do this?” said Mr. Heicklen, whose former colleagues recall him as a talented and unconventional educator. “You don’t have to be a genius to figure this thing out.”

Prosecutors declined to comment on his case, as did Sabrina Shroff, a lawyer who was assigned to assist Mr. Heicklen. (He is acting as his own lawyer.)

He said his activism on nullification dated back to just after he retired in the early 1990s, when he openly smoked marijuana in State College, Pa., to get arrested as a protest against marijuana laws. For this, he was arrested about five times. Mr. Heicklen has said that he otherwise does not smoke marijuana.

Around the same time, he learned about a group called the Fully Informed Jury Association, which urges jurors to nullify laws with which they disagree. Mr. Heicklen, of Teaneck, N.J., said he distributed the group’s materials as well as his own.

“I don’t want them to nullify the murder laws,” he said. “I’m a big law-and-order guy when it comes to real crime.”