The assumption that a certain thing is true, and which gives to a person or thing a quality which is not natural to it, and consequently establishes, a certain disposition, which, without the fiction, would be repugnant to reason and to truth. It is an order of things which does not exist, but which the law prescribes or authorizes. It differs from presumption because it establishes as true, something which is false; whereas presumption supplies the proof of something true.
The law never feigns what is impossible. Fiction is like art; it imitates nature, but never disfigures it. It aids truth, but it ought never to destroy it. It may well suppose that what was possible, but which does not exist; but it will never feign that what was impossible actually is.
Fictions were invented by the Roman praetors who, not possessing the power to abrogate the law, were nevertheless willing to derogate from it under the pretence of doing equity. Fiction is the resource of weakness which, in order to obtain its object, assumes as a fact what is known to be contrary to truth: when the legislator desires to accomplish his object, he need not feign, he commands. Fictions of law owe their origin to the legislative usurpations of the bench.
It is said that every fiction must be framed according to the rules of law, and that every legal fiction must have equity for its object. To prevent their evil effects, they are not allowed to be carried further than the reasons which introduced them necessarily require.
The law abounds in fictions. That an estate is in abeyance; the doctrine of remitter, by which a party who has been disseised of his freehold and afterwards acquires a defective title, is remitted to his former good title; that one thing done today, is considered as done at a preceding time by the doctrine of relation; that because one thing is proved, another shall be presumed to be true, which is the case in all presumptions; that the heir, executor, and administrator stand by representation in the place of the deceased are all fictions of law. "Our various introduction of John Doe and Richard Roe; our solemn process upon disseisin by Hugh Hunt; our casually losing and finding a ship (which never was in Europe) in the parish of St. Mary Le Bow, in the ward of Cheap; our trying the validity of a will by an imaginary wager of five pounds; our imagining and compassing the king's death, by giving information which may defeat an attack upon an enemy's settlement in the antipodes; our charge of picking a pocket or forging a bill with force and arms; of neglecting to repair a bridge, against the peace of the king, his crown and dignity are circumstances, which, looked at by themselves, would convey an impression of no very favorable nature, with respect to the wisdom of our jurisprudence."