That's a good point. The above defendant was not acqitted on the doctrine of provocation, but on the judge's determination that his conduct of attempting to remove the placard didn't satisfy the elements of the offense. I've seen people convicted of that summary offense for less.

Provocation did originate under English common law and I believe it was limited to murder charges, and could only reduce the charge to manslaughter.

In some jurisdictions provocation or "Fighting words" is not a defense to assault, but a separate charge against the prvocateur. When used as a defense, it is applied in a limited fashion. theassault must be contemporaneous with the provocation, which must be of a shocking nature.

the only time I saw it used effectively as a defense was in a case where a defendant struck a shop owner after a verbal disagreement. The shop owner told him to leave and take his "ni***r kids" with him.

My colleqague, who represented the defendant, spoke with a few of the jurors and learned that6-7 jurors were ready to acquit immediately, but the other five examined several facts, such as the proximity of the two people, the fact that there were several people present, including the children, and the immediacy of the reaction.

I don't know that it is being used effectively as a defense very often, but when it is, it is always accompanied by a a cautionary, restrictive instruction from the bench.

I agree that persistent or expansive use of the doctrine will encourage irresponsible behavior, taking the law into one's own hands, and lawlessness.