difficulties, there is no reason why we should not generalize, as the civil law did at the beginning of the last century; and such a generalization was attempted in the last third of the nineteenth century. It became orthodox common law that liability was a corollary of fault. So far as established common-law rules imposed a liability without fault, they were said to be historical exceptions, and some of our courts, under the influence of this theory, were willing to go a long way in abrogating them. Liability, without regard to fault, for the acts of servants and employees was reconciled with this theory by the fiction of representation, exposed long ago by Mr. Justice Holmes and later by Dr. Baty. Finally it came to be thought that no liability without fault was not merely common law but was natural law and that any legislative imposition of such liability was arbitrary and unreasonable in itself and hence unconstitutional. On that theory, the New York Court of Appeals held workmen's compensation unconstitutional, and a minority of the Supreme Court of the United States recently announced the same proposition. Because of its implications for constitutional law, in view of the increasing frequency of legislation imposing responsibility at one's peril in certain enterprises, in the case of certain dangerous agencies and in situations where it is felt that the loss should be borne by all of us rather than by the luckless individual who chances to be hurt, the basis of tort liability has become a question of moment beyond the immediate law of torts. It is a practical question of the first importance, as well as a theoretical question of interest, whether we are to generalize our whole system of tort liability by means of one principle of liability for fault and for fault only, as the French sought to do and as we later sought to do largely under their influence, or, on the other hand, are to admit another source of delictal liability alongside of fault, as the French law does in fact and is coming to do in theory, and as our law has always done in fact. For in our law as it stands one may perceive readily three types of delictual liability: (1) Liability for intentional harm, (2) liability for unintentional culpable harm, (3) liability in certain cases for unintended non-culpable harm. The first two comport with the doctrine of no liability without fault. The third cannot be fitted thereto. We must either brand cases of the third type as historical anomalies, of which we are gradually to rid ourselves, or else revise our notions of tort liability. Let us remember that the nineteenth century was well advanced before we understood the subject of negligence and that before we had convinced ourselves that no liability without fault was orthodox common law, the highest court of England had given absolute liability a new field by the decision in _Rylands_ v. _Fletcher_. We are not questioning a long-established