Damnum iniuria datum was a delict of Roman law relating to the wrongful damage to property.
[1] The law of the Empire on this topic is mainly based on the Lex Aquilia, of which the date is uncertain, but earlier than the introduction of the contract of mandate.
It does not seem that, as the Institutes rather suggest, and the Digest actually says, it superseded earlier provisions as matter of law, but it was of overwhelming practical importance and seems to have swamped them.
[1] The Lex Aquilia contained, besides a penalty for adstipulatores who fraudulently released the debtor and, perhaps, a vaguely indicated procedure for multa as an alternative, in the case which does concern us, two important provisions for a civil remedy for damage to property.
Its first chapter provided that anyone who unlawfully killed another's slave or beast within the class of pecus, was liable to pay the owner the highest value the thing had had within the previous year.
The third chapter did not, like the first, say the highest ("plurimi") value within the 30 days, but the lawyers read this in, in order to give the provision a meaning.
[3] The actio legis Aquiliae was a penal action with the ordinary consequence that it did not lie against the heres, except to the extent of his enrichment, that it was not extinguished by capitis deminutio, and that each of joint wrongdoers was liable in full.
The rule that it was duplex contra infitiantem, a result of the original manus iniectio, raises the question whether denial was of the facts or of liability.
We are told that one who confesses the fact of killing could not afterwards deny liability, but might prove that the man was not dead, or died from natural causes.
But if the original act was wilful it is generally held, though there is no explicit text, that intervening negligence of the injured person was no defence, though there was the same breach of causal nexus.
At one time it seems that it was inferred from the etymology of the word "occido" that the act must have been done directly by the person of the wrongdoer or a weapon held by him.
[7] The rule so understood was expressed in the words that it must be "corpori corpore", by the wrongdoer's body to that of the injured thing.
Another extension made at civil law by interpretatio, was to understand "rumpere" in the third chapter to mean "corrumpere", so that it covered any form of material damage and the other words became unimportant.
[7] Further, in construing the words "highest value" the jurists included what is called "damnum emergens," loss due to extrinsic circumstances, and "lucrum cessans", profit which the fact prevented the owner from making.
The praetor provided an actio utilis, or one in factum, to persons with lesser property rights in the thing, e.g. the usufructuary, alongside the owner.
The praetor gave an action, utilis or in factum where it was by but not to the body, as by throwing grain into a river: it might not be harmed, but in effect it was destroyed.