Roman legal sources do not report 'cases' in the common-law sense; there are no transcripts of trials, no named parties or recorded judgments. Instead, the classical jurists presented hypothetical facta and quaestiones—fact patterns and legal questions—on which they offered responsa (advisory opinions). These opinions, later excerpted in the Digest, function as 'landmark authorities' in Roman law pedagogy.
Ulpian on the pruner: negligence and the duty to warn
One of the most frequently cited illustrations of Aquilian negligence concerns a workman pruning trees near a public path. Ulpian (D.9.2.31 pr., drawing on earlier jurists) discusses the liability of a pruner who fails to shout a warning and thereby causes a falling branch to kill a passing slave. The question is whether the pruner acted iniuria. Ulpian concludes that he did: a reasonable person (bonus paterfamilias) would have called out; failure to do so constitutes culpa. The text refines the standard: if the location was such that the pruner could not foresee passers-by, liability might not attach; but on a frequented road, the duty to warn is clear. This fragment illustrates the Roman development of a fault-based standard akin to modern negligence.
Labeo and the doctor: professional negligence
Another celebrated set of problems concerns medical malpractice. Labeo, an Augustan jurist, considered whether a physician who negligently treated a slave, causing his death, incurred Aquilian liability (D.9.2.8 pr.). He held that a doctor who operated imperite—unskilfully or recklessly—was liable, but one who exercised reasonable professional judgment was not, even if the patient died. This anticipates the modern distinction between error of judgment and breach of duty. Proculus endorsed Labeo's view, and later jurists followed suit, refining the inquiry into what counted as imperitia. The cases emphasise that culpa is context-sensitive: a trained physician is held to the standard of his profession, not merely that of a layperson.
Celsus on causation: pushing versus throwing
Celsus, a jurist of the second century CE, grappled with the boundaries of occidere in a series of hypotheticals (D.9.2.7.6). Suppose the defendant pushes a slave off a bridge without touching him directly—is that occidere corpore? Celsus argued it was not; the statutory action required bodily contact between defendant and victim (corpore corpori). Pushing an object that then strikes and kills the slave might qualify, but merely frightening or manoeuvring the slave into danger did not. However, Celsus acknowledged that an actio in factum could provide a remedy. His rigorous parsing of occidere demonstrates the Roman commitment to strict statutory interpretation, balanced by equitable praetorian extensions.
Ulpian on matched pairs: valuation and consequential loss
Ulpian addressed whether the killing of one slave in a matched pair (for instance, twins trained as litter-bearers, or actors in a troupe) entitled the owner to recover not just the dead slave's value but also the depreciation of the survivor (D.9.2.22.1). He held that the peak-value formula could include the premium attributable to the pairing: the slave was worth more as part of a set, and that enhanced value—assessed within the year—was recoverable. But the loss in value of the surviving slave was harder to capture under chapter one; some jurists suggested a separate action for that consequential harm, or recovery under chapter three. This line of cases reveals the jurists' sensitivity to commercial realities and their willingness to stretch valuation principles to achieve fair compensation.
Julian on self-defence: the slave who attacks
Julian, another leading second-century jurist, considered whether killing another's slave in self-defence gave rise to liability (D.9.2.4 pr., D.9.2.45.4). He concluded that if the defendant faced imminent unlawful violence and used proportionate force, there was no iniuria; the killing was justified. But if the defendant used excessive force, or if the threat was not immediate, liability could attach. This defence of necessity and self-defence became a standard exception to Aquilian liability, and Julian's casuistry—examining degrees of threat and proportionality—set the template for later analysis.
Paul on veterinary care: professional standards for animal doctors
Paul (D.9.2.8.1) extended the professional-negligence analysis to veterinarians (mulomedicus). If a vet negligently treated a horse or mule, causing its death, he was liable under the lex Aquilia. The standard was one of reasonable skill in the veterinary art; mere failure to cure, absent negligence, did not suffice. This demonstrates the generality of the Aquilian fault principle: it applied to all defendants, whether lay or professional, adjusting the standard of care to reflect expertise and role.
These fragments, while not 'cases' in the modern sense, are the building blocks of Roman Aquilian doctrine. They show the jurists at work: interpreting terse statutory language, testing it against diverse facts, and refining legal principles through reasoned disagreement.