ignorance of law, in almost all cases, and ignorance of fact, in a very large class of cases, is no excuse. And, considering the matter historically, we are justified in laying down the general principle that Ignorantia neminem excusat, and in treating all cases in which ignorance is an excuse as exceptions which have in some way managed to prevail against the rule.

What then is the historical origin of this principle? I believe it to be derived from an old rule of evidence which, though now obsolete as a rule of evidence, has left important traces in the substantive law. This rule was that knowledge and intention were not triable. The recognition of this rule in early English law sufficiently appears from the following citations. In 17 Edward IV. (1) Chief Justice Brian says: "It is common learning that the thought of man is not triable, for the devil himself knoweth not the thought of man." A few years earlier it was said: "This is no issue, for here he has justified in order to view the waste, and if issue ut supra were taken, his intent would be put in trial, which cannot be." (2) So, in 21 Henry VII. (3) Chief Justice Reede says: "The intent cannot be construed." And, as late as the reign of Charles II., it is said of the defendant in trespass : "His intention and knowledge are not traversable ; (1) Y. B. 17 Ed. IV. 2.

(2) Y. B. 12 Ed. IV. 10, pl. 28.
(3) Y. B. 21 Henry VII. 28, pl. 5.

they cannot be known." (1)

Such a rule is almost

inevitable in early law. Primitive methods of trial are instruments far too coarse for any such delicate enquiry as that into knowledge or intention. Overt acts are

alone capable of proof. (2)

§ 8. Since knowledge was thus not triable, it was necessary that it should be conclusively presumed. Hence the rule that ignorance is no defence, and hence the instances of absolute liability founded upon that rule. The rule that ignorance of law is no defence is of course still recognised, and its foundation upon a real or supposed impossibility of proof has not been lost sight of. "If ignorance of the law should excuse in the law," says the Student of the Common Law, "many offenders would pretend ignorance." (3) And modern legal theorists defend the rule on the same ground. (*) The rule that ignorance of fact is no excuse has, on the other hand, ceased to be recognised in this form, and has become transformed into the already stated rule that a person is absolutely liable for all voluntary interference with person or property.

(1) Basely v. Clarkson, 3 Lev. 37.

(2) Compare the rule that the thought of man is not triable with Hale's reason why witchcraft was no felony at common law : "Because no external act of violence was offered whereof the common law can take notice, and secret things belong to God." 1 H. P.C. 429.

(3) Dialogue II., Ch. 46.

(4) Austin's Jurisprudence, I. 483, 5th ed.

That this rule of absolute liability is in reality merely a transformation of the rule of evidence, that the thought of man is not triable, is a proposition which cannot be supported by any great body of direct evidence. Such rules of evidence have a strong tendency to transform themselves into independent rules of substantive law, the original foundation of which becomes soon forgotten. Still we occasionally find the rule of absolute liability in question expressly attributed to its original source. Thus, in a case of the reign of Charles II., to trespass for cutting the plaintiff's grass the defendant pleaded that "in mowing his own land, he involuntarily and by mistake mowed down some grass growing upon the balk and hade of the plaintiff, intending only to mow the grass upon his own balk and hade. Upon this the plaintiff demurred, and had judgment; for it appears the fact was voluntary, and his intention and knowledge are not traversable; they cannot be known." (') So in 7 Henry IV. (2) the same reason is given for the absolute liability of one who arrests on suspicion of felony, where no felony has been committed: "If any felony is done in pais, and upon this a man is arrested on suspicion of this felony, the arrest is good, because there is a special cause of suspicion. But if any man might arrest another because of suspicion, then any imprisonment might be legally (1) Basely v. Clarkson, 3 Lev. 37. (2) Y. B. 7 Henry IV. 35, pl. 3.

justified.. If a special cause has happened before arrest, then the thing may well be tried per pais. But if such an arrest is made per un supposal without any felony committed beforehand, then the cause of arrest would be tried by the imagination of a man in his own heart, which cannot be."

§ 9. It may be objected that, if this explanation is true, absolute liability would have existed in all cases whatever, and not merely in certain exceptional cases. If intention and knowledge were not triable, and were therefore conclusively presumed, all injuries would have been regarded as intentional, and would have given rise to liability. While, so far from this being the case, no such absolute liability was ever recognised by the criminal law, and even in the case of civil procedure, the existence of the action of trespass on the case for negligence proves that no such presumption of intention could have been recognised even in the earliest times.

But in the first place, the case of criminal liability was always recognised as an exception to the rule that intent was not triable. "The intent of a man," it is said in a case of the reign of Edward IV., "will be tried in robbery." (1) Criminal liability was too serious a thing to be imposed on innocent men, merely for the sake of facilitating the administration of justice. Difficult as it was to try the thought of a man,

(1) Y. B. 12 Ed. IV. 10, pl. 28; see also Y. B. 21 Henry VII. 28, pl. 5, and Y. B. 6 Ed. IV. 7, pl. 18.

it was felt necessary to make the attempt in matters of life and death.

In the second place, the existence of the action of trespass on the case for negligence was, rightly considered, perfectly consistent with the rule that intent was not triable. Negligence is, properly speaking, not a state of mind at all. It is the opposite, not of intention, but of carefulness or diligence. It is the breach of the duty of taking care. And the recognition of such a duty, and of the breach of it, constituted no exception to the rule as to intention which is now under consideration. The distinction between trespass and trespass on the case for negligence, was not that in the former case the injury was intentional, and in the atter was not, but that in the former case the injury was the direct act of the defendant, while in the latter it was merely the consequence of an act of his, namely, his breach of the duty of carefulness. If John Styles allowed his fire to burn his neighbour's house, he was sued, not in trespass, but in case, the reason being, not that the damage done was unintentional, but that it was not the act of John Styles at all. He did not, in the eye of the law, burn down his neighbour's house; he merely neglected to take care that it was not burnt down. (1)

The early recognition of liability for negligence is

(1) See Blackstone's Comm. III. 123; also the judgment of Sir W. Blackstone in Scott v. Shepherd, 2 W. Bl. 894.