Police dread the inevitable call to intervene in a domestic dispute. Two people who seem about to kill one another will vent their collective wrath on the officer who was only trying to restore peace.
Of course such intervention is the peace officers' public commission. They are the only exception to Proverbs 26:17's injunction: Laying hold on the ears of a dog, [Is] a passer-by making himself wrath for strife not his own.
Where does that principle end, however, when a passer-by witnesses abuse or bullying in progress? If I have the ability to subdue a bully would I violate Proverbs 26:17 by doing so? Let's see what the meddler in that verse is actually doing.
A "passer-by" is a stranger. By definition, he is completely ignorant of the situation he witnesses. The person who seems to be bullying may, in fact, be justified in his action. But what if one of the parties in the dispute welcomes the stranger's involvement, or has actually solicited it? Does that guarantee the stranger is taking the right side of the argument? He bases his intervention on a brief moment's observation or one party's version of a confrontation that may have been years in the making. He has no guarantee that his assessment is based on truth.
"Making himself wrath" means the passer-by unilaterally assumes the role of avenger. If he is uninvited, both parties in the dispute may resent his intervention. He has, in effect, grabbed a fierce dog by the ears.
Often the meddler fancies himself as a mediator when, in fact, he has taken up one party's offense against the other. He is blinded by his own bias, exacerbating rather than ameliorating the situation.
So, when should a stranger intervene? When he can remain unbiased, and function as a peacemaker rather than a judge. And if he can avoid being shot or stabbed, that would be a distinct bonus.