In fact, if you expect to get hit with a prosecution motion to exclude necessity and the First Amendment, there's no reason not to refer to those defenses in public discourse. At least they're easy for the public to understand. And it will help keep your other defenses under wraps. Because other judges have done so in the past. Judges rely on case law, also called precedent.
Precedent is created through appeals.
That is, a defendant goes to trial and is convicted. Their written reasoning, called an opinion, is precedent. And trial judges are supposed to follow these written opinions. Unless you convince your judge that the facts of your particular case are sufficiently different from the precedent, the judge will feel quite comfortable in denying your argument. In some states there have been many protestor trials, quite a few of which have resulted in appeals.