PRINCIPAL, in law, is either the actor or absolute perpetrator of the crime, who is called a principal, in the first degree; or he who is present, aiding and abetting the fact to be done, who is denominated a principal in the second degree. The presence of a principal need not always be an actual immediate standing by, within sight or hearing of the fact; but there may be also a constructive presence, as when one commits a robbery or murder, and another keeps watch or guard at some convenient distance. And this rule has also other exceptions; for, in case of murder by poisoning, a man may be a principal felon by preparing and laying the poison, or giving it to another (who is ignorant of its poisonous quality) for that purpose; and yet not administer it himself, nor be present when the very deed of poisoning is committed. And the same reasoning will hold, with regard to other murders committed in the absence of the murderer, by means which he had prepared beforehand, and which probably could
not fail of their mischievous effect. As by laying a trap or pit-fall for another, whereby he is killed; letting out a wild beast, with an intent to do mischief; or exciting a madman to commit murder, so that death thereupon ensues: in every one of these cases the party offending is guilty of murder as a principal, in the first degree. For he cannot be called an accessory, that necessarily pre-supposing a principal; and the poison, the pit-fall, the beast, or the madman, cannot be held principals, being only the instruments of death. As therefore he must be certainly guilty, either as principal or accessory, and cannot be so as accessory, it follows that he must be guilty as principal; and if principal, then in the first degree; for there is no other criminal, much less a superior in the guilt, whom he could aid, abet, or assist.