Laws against jury tampering are intended to deter people from threatening or intimidating jurors. To contort these laws to justify punishing Mr. Heicklen, whose court-appointed counsel describe him as “a shabby old man distributing his silly leaflets from the sidewalk outside a courthouse,” is not only unconstitutional but unpatriotic. Jury nullification is not new; its proponents have included John Hancock and John Adams.

The doctrine is premised on the idea that ordinary citizens, not government officials, should have the final say as to whether a person should be punished. As Adams put it, it is each juror’s “duty” to vote based on his or her “own best understanding, judgment and conscience, though in direct opposition to the direction of the court.”

In 1895, the Supreme Court ruled that jurors had no right, during trials, to be told about nullification. The court did not say that jurors didn’t have the power, or that they couldn’t be told about it, but only that judges were not required to instruct them on it during a trial. Since then, it’s been up to scholars like me, and activists like Mr. Heicklen, to get the word out.

Nullification has been credited with helping to end alcohol prohibition and laws that criminalized gay sex. Last year, Montana prosecutors were forced to offer a defendant in a marijuana case a favorable plea bargain after so many potential jurors said they would nullify that the judge didn’t think he could find enough jurors to hear the case. (Prosecutors now say they will remember the actions of those jurors when they consider whether to charge other people with marijuana crimes.)

There have been unfortunate instances of nullification. Racist juries in the South, for example, refused to convict people who committed violent acts against civil-rights activists, and nullification has been used in cases involving the use of excessive force by the police. But nullification is like any other democratic power; some people may try to misuse it, but that does not mean it should be taken away from everyone else.