Another consideration affecting the argument that the law as to trespasses upon property establishes a general principle, is that the defendant’s knowledge or ignorance of the plaintiff’s title is likely to lie wholly in his own breast, and therefore hardly admits of satisfactory proof.  Indeed, in many cases it cannot have been open to evidence at all at the time when the law was settled, before parties were permitted to testify.  Accordingly, in Basely v.  Clarkson, 1 where the defence set up to an action of trespass quare clausum was that the defendant in mowing his own land involuntarily and by mistake mowed down some of the plaintiff’s grass, the plaintiff had judgment on demurrer.  “For it appears the fact was voluntary, and his intention and knowledge are not traversable; they can’t be known.”

This language suggests that it would be sufficient to explain the law of trespass upon property historically, without attempting to justify it.  For it seems to be admitted that if the defendant’s mistake could be proved it might be material. 2 It will be noticed, further, that any general argument from the law of trespass upon laud to that governing trespass against the person is shown to be misleading by the law as to cattle.  The owner is bound at his peril [100] to keep them off his neighbor’s premises, but he is not bound at his peril in all cases to keep them from his neighbor’s person.

The objections to such a decision as supposed in the case of an auctioneer do not rest on the general theory of liability, but spring altogether from the special exigencies of commerce.  It does not become unjust to hold a person liable for unauthorized intermeddling with another’s property, until there arises the practical necessity for rapid dealing.  But where this practical necessity exists, it is not surprising to find, and we do find, a different tendency in the law.  The absolute protection of property, however natural to a primitive community more occupied in production than in exchange, is hardly consistent with the requirements of modern business.  Even when the rules which we have been considering were established, the traffic of the public markets was governed by more liberal principles.  On the continent of Europe it was long ago decided that the policy of protecting titles must yield to the policy of protecting trade.  Casaregis held that the general principle nemo plus juris in alium transferre potest quam ipse habet must give way in mercantile transactions to possession vaut titre. 1 In later times, as markets overt have lost their importance, the Factors’ Acts and their successive amendments have tended more and more in the direction of adopting the Continental doctrine.

I must preface the argument from precedent with a reference to what has been said already in the first Lecture about early forms of liability, and especially about [101] the appeals.  It was there shown that the appeals de pace et plagis and of mayhem became the action of trespass, and that those appeals and the early actions of trespass were always, so far as appears, for intentional wrongs. 1