Caput IX. Lex Aquilia: Defensor
by Michael Lambert
March 2026
Caput VIII. Lex Aquilia: Precatorem Parare
by Michael Lambert
March 2026
Caput IX. Lex Aquilia, Defensor
reus debes ad praesens, reddendas in futuro (quam primum futuro est)
The defendant owes at present, payable in the future (how soon is the future)
Said of the plaintiff confronted by a recalcitrant defendant
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Roman Law and the Citizen
Roman Law and the Citizen series was presented in January 2025
We continue to explore the development and maturation of Roman jurisprudence. You, as a Roman citizen during the Principate era, what are your legal options to redress iniuria, ‘harm’ committed against self?
This six-part series continues in two, three-month segments during the period January-March and July-September
(To familiarize yourself with Roman jurisprudence, consult the introduction: January 2025)
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dedititii
One who has capitulated
Said of a manumitted slave, subject to perpetual legal disability
Introduction
This caput, chapter focuses on the defensor, the defendant
If you have followed the series, commencing January 2025; the Roman jurist is shamelessly quoted. The jurists’ voices, their comments and opinions – through written, in some instances two millennia past, retain a presence for our lives
Though we no longer drive a quadriga, a four, “horsepower” chariot; the basic business of “cornering the via, the way” remains much the same. Hence, Roman jurists refer to these private legal actions as delicts, which represent the harm suffered by an individual, the free borne citizen
By chance the obiter dicta written by the jurists survive the fall of the Roman Empire. Further, by chance these private and learned writings were read and consequently form much of the basis of current era jurisprudence. The cited cases are from primary sources, which convey an immediacy and presentment to the – dry – legal renderings. Most, if not all, obiter dicta are attributed to Principate era, approximately from 30 BCE to 235 CE
Byzantium emperors saw themselves the inheritors of Romand jurisprudence and therefore, the successors of the Roman Empire. Justinian’s Digest was promulgated at Constantinople in 253 CE. In all, the Digest comprises more than nine thousand excerpts of Classical era juristic scribblings
Our era’s concept of jurisprudence evolves from our understanding of basic, fundamental concepts, in particular those of Gaius, his elementary textbook the Institutes, circa 160 CE. The Institutes is the sole surviving legal work of the Principate
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qui iure suo utitur neminem laedit
He who exercises his legal right inflicts upon no one any injury
Said by those who sneer, who assert their right
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The Cases give an insight into daily life, the behaviour and attitudes, of lives lead
Cases cited below: LXXXII to XCV
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Ulpianus1. D.9.2.11.1-2. in the eighteenth book on the Edict. obiter dictum. Multiple Defendants. Lex Aquilia. liability | |||
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si alius tenuit, alius interemit, is qui tenuit, quasi causam mortis praebuit, in factum actione tenetur. sed si plures servum percusserint, utrum omnes quasi occiderint teneantur, videamus. et si quidem apparet cuius ictu perierit, ille quasi occiderit tenetur, quod si non apparet, omnes quasi occiderint teneri Iulianus ait, et si cum uno agatur, ceteri non liberantur, nam ex lege Aquilia quod alius praestitit, alium non relevat, cum sit poena | If he (the victim) was held by one person and killed by another, the person who held is liable in an in factum action for furnishing the cause of death. But if several persons struck a slave, let us see whether all are liable for slaying him. If indeed it is clear who struck the fatal blow, that person is liable for slaying, but if it is unclear, Iulius says that all are liable for the saying, and the rest are not released if one is sued. For under the lex Aquilia what one person pays does not release another, since it is a penalty | ||
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Footnote. | 1 | Ulipianus, a jurist | |
The issue for a court, then and now; on joining two or more defendants together in the same action has – from the court’s perspective, an economy of prosecution
Ulipianus addresses the central issue of co-defendants: sed si plures servum percusserint, utrum omnes quasi occiderint teneantur, videamus. et si quidem apparet cuius ictu perierit, “But if several persons struck a slave, let us see whether all (emphasis added) are liable for slaying him If indeed it is clear who (emphasis added) struck the fatal blow”
Iulianus, a jurist, asserts the following obiter dictum from the late-Republican era: (a case involving simultaneous defendants) each of them (defendants) is cumulatively liable under the lex Aquilia
Iulianus further asserts the argument: utilitas communis, the common good is the guiding principle for co-defendants, several actors involved in one act
Case LXXXIII
Ulpianus1. D.9.4.2 pr. in the eighteenth book on the Edict. obiter dictum. Noxal Liability. Lex Aquilia. liability | |||
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si servus sciente domino occidit, in solidum dominum obligat, ipse enim videtur dominus occidisse, si autem insciente, noxalis est, nec enim debuit ex maleficio servi in plus teneri, quam ut noxae eum debat | If a slave slays with his master’s knowledge, he obligates the master in full, for the master himself is considered to have slain, but if with him unaware, there is a noxal action, since on his slave’s wrongdoing he ought not to be liable for more than noxal surrender | ||
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Footnote. | 1 | Ulipianus, a jurist | |
In the action, if the master is unaware of the slave’s act, then the master is not liable for the act under lex Aquilia. (A slave is a thing, not a person, therefore; not responsible for own acts.) In actions when the slave owner was aware, the master is obliged to either pay a sum not higher than the slave’s actual worth to the plaintiff or surrender the slave to the plaintiff. Surrendering a slave from one master to another master is known as noxal surrender
A paterfamilias, the senior male head of an extended Roman family group, may have noxal liability for the wrongful loss inflicted by a free person in his power. The paterfamilias surrenders the offender under a form of debt-bondage: mancipium. The offender works off the debt. Once paid, the plaintiff is obliged to hand back the free born person to the paterfamilias
Since a slave is not a person but a thing, therefore; the thing is not liable for culpa, a “blame”, but may be held for damnum iniuria datum, “damage unlawfully inflicted”. Noxal debt follows a slave. Therefore, the Romans observed an elaborate business process during either sale or purchase of a slave. The process guaranteed neither the former owner nor the new owner will be liable for dolus, “fraud”
Nota bene: A manumitted slave, being a former slave; a noxal liability may follow as a free person
Nota bene: See LXXXV, the bonae fidei possessori, the “good faith possessor” concerning debts following the sale or purchase of a slave
Case LXXXIV
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Gaius1. D.9.2.32 pr. in the seventh book on the Provincial Edict. obiter dictum. Slaves Act Together. Lex Aquilia. liability | |||
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illud quaesitum est, an quod Proconsul in furto observant quod a familia factum sit (id est ut noninsingulos detur poenae persecution, sed sufficeret id praestari, quod praestandum foret, si id furtumunus liber fecisset), debeat et in actione damni iniuriae observari. sed magis visum est idem esse observandum, et merito, cum enim circa furti actionem haec ratio sit, ne ex uno delicto tota familia dominus careat eaque ratio similiter et in actionem damni iniuriae interveniat, sequitur ut idemdebeat aestimari, praesertim cum interdumlevior sit haec causa delicti, veluti si culpa et nondolo damnum daretur | It was asked whether the rule used by Proconsuls for theft (furtum) committed by a household of slaves – namely, that pursuit of the penalty not be granted against individual slaves, but that it suffices if payment is made of what would be owed if one free person had committed the theft – ought also to be followed in the action for wrongful loss. But it seemed preferable that the same rule be followed, and deservedly. For the reasoning in the action on theft is that the owner (does) not lose his whole household because of one case (delict); this reasoning has similar force in the action for wrongful damages. It follows that the same evaluation should be made, especially since this form of delict is sometimes less serious, e.g., if loss is inflicted by culpa and not by dolus | ||
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Footnote. | 1 | Gaius, a jurist | |
The obiter dictum cites the Praetor Urbanus, the “Urban Praetor” who first formulated the rule regarding theft, pursue not the action not against a single slave, but against the group of slaves as if the group were one person.
To some extent the application of the Praetor Urbanus undermines the punitive basis of Aquilian liability
Case LXXXV
The central issue of the action is summed in the opening sentence of the action, servi autem occidentis nomine dominus tenetur, si vero cui bona fide servit non tenetur, “The owner is liable in the name of a slave who slays, but a person whom he (the slave) serves in good faith is not liable”
Ulipianus annunciates Roman jurisprudence clearly and concisely
bonae fidei possessori, a “good faith possessor” holds property that belongs to another person the property owner may reclaim their loaned property at any time. Depending on the property possessed, there may be accrual of expenses. If “yes”, the good faith possessor may retain the property if the owner does not compensate the possessor
The chief distinction between the property owner and the “good faith possessor” the property owner retains legal possession and control of the property throughout the period of the loan to another, therefore; any or all liabilities or costs that occur are to the property owner
Case LXXXVI
Ulpianus1. D.9.2.27.1 in the eighteenth book on the Edict. obiter dictum. Co-owned Slave, Suit Between Owners. Lex Aquilia. liability | |||
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si servus communis, id est meus et tuus, servvum meum occiderit. Legi Aquiliae locus est adversuste, si tua voluntate fecit, et ita Proculum 2 existimasse Urseius 3 refert. quod si non voluntate tua fecit, cessare noxalem actionem, ne sit in potestate servi, ut tibi soli serviat, quod puto verum esse | If a co-owned slave. i.e., one belonging to you and I, slays my slave, the lex Aquilia applies against you if he did it by your will, Urseius reports that Proculus also thought this. But if he did not act by your will. (Proculus adds that) the noxal action fails, least the slave have it in his power to serve you alone. I consider this view correct | ||
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1 | Ulipianus, a jurist | ||
| 2 | Proculus, a jurist | |
| 3 | Urseius, a jurist | |
Ulipianus cites Roman jurisprudence, under lex Aquilia; if the master of a slave has prior knowledge of a future act by a slave, then the slave owner is liable
Two further jurists are cited, Proculus and Urseius; if the master had prior knowledge, then he is liable
The action states noxal surrender also fails (contrary to Roman jurisprudence). Why?
Concerning the Romans, the issue is suit between co-owners and the maintenance of social civility and dignity. If co-owners sue, social structure is perceived to be threatened. The preferred course of legal action is the division of common property
Case LXXXVII
Ulpianus1. D.9.2.44.1 in the forty-second book on Sabinus. obiter dictum. Slave Acts with Master’s Knowledge. Lex Aquilia. liability | |||
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quotiens sciente domino servus vulnerate vel occidit. Aquilia dominum teneri dubium non est | Whenever a slave wounds or slays with his master’s knowledge, there is no doubt that the master has Aquilian liability | ||
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Footnote. | 1 | Ulipianus, a jurist | |
Case LXXXVIII
Paulus1. D.9.2.45 pr. in the tenth book on Sabinus. obiter dictum. Slave Acts with Master’s Knowledge. Lex Aquilia. liability | |||
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scientiam hic pro patientia accipimus, ut qui prohibere potuit teneatur, si non fecerit | We construe knowledge here to mean sufferance, so that a person who could prevent is liable if he does not do so | ||
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Footnote. | 1 | Paulus, a jurist | |
Case LXXXVII correctly cites lex Aquilia, statute law; liability vis-à-vis the master has possession and control of his property, therefore he can control the slave’s acts of iniuria, “harm”. To argue otherwise is to argue against oneself
Case LXXXVIII is best summarized, si neglegens eras, inopia patientia, “if you were negligent, you lack patience” is no defence in support of property ownership and control. The master directs the slave, therefore; no matter how trying the slave’s behaviour may be, the master is in control and therefore is liable
The plaintiff has two options, under statute law of lex Aquilia accepts noxal surrender of the thing, the slave, the market value of the slave or sue in factum; with the hope to gain either equal to or greater than the market value of the thing
Case LXXXIX
The obiter dictum presents two versions of the same incident:
The tenant farmer tells a slave furnaceman to watch a fire in the farmhouse, the slave falls asleep. The fire escapes from the furnace and burns the farmhouse to the ground
The second version, the first slave sets the kindling and logs in the hearth, then lights the whole. The slave departs, a second slave watches the fire. The fire escapes and burns the farmhouse to the ground
Nota bene: The original obiter dictum was re-written (during the collation of juristic writings, the Byzantium era). Both versions agree the fire escapes the furnace which results in burning the farmhouse to the ground. The loss is the entire building
The central issue is either culpa, of “fault” or “responsibility” or dolus, of “malice” for Aquilian liability
Is the tenant farmer liable for the value of the farmhouse?
The slave who set wood in the hearth and lit the stacked wood committed no wrong, the absence of culpa. The slave who fell asleep is ambiguous, in that; the slave did nothing, that is no positive act done required for Aquilian liability
Neratius, a jurist, writes the tenant farmer is liable on the lease if the farmer was careless in choosing the slave, that is; was the slave inexperienced or was tired?
Ulpianus in Case XXXI, the Duty of Care, Medical Treatment, the physician is liable. The doctor performed the medical operation but did not perform the follow-along care. The since the doctor did not fulfill his medical duties competently and completely, he is liable either under contract law or lex Aquilia
Nota bene: See: Caput IV, Case XXXI, Duty of Care. Medical Treatment
Ulpianus provides the correct answer, if the furnaceman is free born, he is liable but if the furnaceman is a slave, the slave is responsible for iniuria, “harm”, but not Aquilian liability
If the furnaceman is a slave, then one course of action is noxal surrender. But, the landlord, the property owner of the leased farmhouse, may want pecuniary compensation in excess of the worth of the slave
Case XC
The hired slave is put in charge of a mule. The slave ties the animal’s rein to his thumb. The mule bolts. The slave’s thumb is torn off. The mule rushes headlong and self-injures, described as ruptum vel debilitatum, “having been either broken or maimed”
What is absent from the case is third party involvement, such as someone or something startling the mule which results in the animal bolting with self-injury. If a third party is present, then both the master, of the slave, and the owner of the mule each have an action under lex Aquilia. The alternate action is the lease agreement
If the master represents the slave as an experienced muleteer, the mule’s owner has an Aquilian action
Gaius, a jurist, in a similar action concerning a muleteer commented mullio erat culpa, si eius carebat incaute, “the muleteer was at fault, if he was without care”. Aquilian liability rests on the principle of damnum iniuria datum, a “loss wrongfully inflicted”, that is; the defendant’s act was wrongful
Since there is neither third party present nor the appearance of inuria, a “wrong”, the issue devolves to the muleteer’s behaviour being simplex, “artless”. Since statute law offers no solution, an in factum action of the mule owner suing the master (of the slave) for pecuniary compensation
Case XCI
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In many respects Case XCI parallels and reinforces the jurisprudence as annunciated in XC
The master is responsible for his slaves: si culpa colonus careret, ceterum si noxios servos habui, “if the slaves act to cause harm, then noxal surrender is applicable”
Crucially the obiter dictum says: si uno iudicio res esset iudicata, altero amplius non agendum, “if the matter is adjudged in one action, there can be no further suit by the other”
Nota bene: Ulpianus asserts an important point of Roman jurisprudence, and by parallel, our era, the Common Law; altero amplius non agendum, “no further suit by the other” is expressed as the: principium contra legitimum duplicibus discrimen, the “principle of double jeopardy” to prevent double punishment for the same act, as well as the unwarranted harassment of the accused by multiple prosecutions
Nota bene: Rome, throughout her history, lacks a comprehensive service to suppress fire and conflagration. The obiter dictum asserts a wider and inclusive governance, a closing statement applicable to all – rural and urban
Case XCII
Ulpianus1. D.47.10.15.46. in the eighteenth book on the Edict. obiter dictum. Action on Outrage (Affirmation – Cumulative Punitive Actions). Lex Aquilia. liability | |||
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Si quis servo verberato iniuriarum egerit, deinde postea damni iniuriae agat, Labeo scribit eandem rem non esse, quia altera actio ad damnum pertineret culpa datum, altera ad contumeliam | If a person, whose slave was thrashed, sues for outrage (iniuria) and then later for wrongful damage (damni iniuriae), Labeo writes that this is not the same cause of action, since the second action concerns loss inflicted by fault (culpa), while the first concerns insult (to the master of the slave) | ||
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Footnote. | 1 | Ulpianus, a jurist | |
| 2 | Labeo, a jurist | |
iniuria, “outrage” and culpa, “fault” have different qualities
iniuria is an act outside of ius, “right”, in other words, an act committed contra ius, “contrary to right”
Aquilian statute law allows an action on iniuria. Statute law permits two simultaneous interpretations: one for loss, the other for insult. iniuria is a loss inflicted by culpa, even by a person who did not wish to do harm. In this instant, iniuria is an injury to the defendant
The Praetor Urbanus, the “Urban Magistrate” is the senior jurist responsible for the administration of justice and the running of the law courts. Requested to comment, the Praetor Urbanus provides a judicial comment concerning where iniuria lies in an action involving a slave and a master. The comment is concise and clear: nulla iniuria servus, sed iniuria ad dominum, “no wrong to the slave, but the wrong (suffered is) to the Lord (master of the slave)”
Roman jurisprudence allows cumulation of punitive actions, example: a person seduces another master’s serva, a “female slave”. Two Aquilian actions are permitted: the first is on outrage and the second on corrupting the slave
Nota bene: See Case XCIII, below. A dissenting juristic statement concerning cumulative punitive actions
Case XCIII
Paulus1. D.44.7.34. in the monograph on Concurrent Actions. obiter dictum. Action on Outrage (Dissent – Cumulative Punitive Actions). Lex Aquilia. liability | |||
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qui servum alienum iniuriose verberat, ex uno facto incidit et in Aquiliam et in actionem iniuriarum, iniuria enim ex affect fit, damnum ex culpa et ideo possent utraeque competere. Sed quidam altera elec ta alteram consume. Alii per legis Aquiliae actionem iniuriarum consume, quoniam desiit bonum et aequum esse condemnari eum, qui aestimationem praestitit, sed si ante iniuriarum actum esset, teneri eum ex lege aquilia sed haec sententia Praetorem inhibenda est, nisi in id, quod amplius ex lege Aquilia competit, agatur. Rationabilius itaque est eum admitti sententiam, ut liceat ei quam voluerit actionem prius exercere, quod autem amplius in altera est, etiam hoc exsequi | A person who wrongfully beats another’s slave is liable from one act both to the Aquilian action and to the action on outrage (iniuria), for the iniuria arises from intent, the loss from fault (culpa), and so both can lie. But some (hold) that the action on outrage is consumed by that under the lex Aquilia, since it ceased to be good and fair that a person be condemned who had (already) proffered the evaluation (of the loss), but if action is brought first on the outrage, he is liable under the lex Aquilia. but this view should be restricted by the Praetor unless suit is brought (only) for the excess over what is due under the lex Aquilia. and so it is more reasonable that this view be accepted, that he be permitted to bring first the action he prefers, and then also to recover the excess in the other action | ||
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Footnote. | 1 | Paulus, a jurist | |
Iulius Paulus, “Julius Paulus” was a jurist during the Late Classical era, 190 to 235 CE
Under men who held the office of Praetor Urbanus, Roman jurisprudence developed and evolved case-based law in response to the narrow constraints of lex Aquilia, statute law
The Paulian obiter dictum, in the opening sentence, cites accepted legal doctrine concerning iniuria, “outrage” and culpa, “fault”. The second sentence onwards is the challenge: Sed quidam altera elec ta alteram consume. Alii per legis Aquiliae actionem iniuriarum consume… et cetra, “and so forth”, principles in one area of law are subsumed under other concurrent principles. Cumulative legal actions occur when multiple legal principles arise from the same set of facts that are delt with simultaneously, ultimately; the issue for the defendant is multiple evaluations of iniuria
The central issue in multiple same facts proceedings, is their complexity of evidence and procedure with the chance of multiple findings for the same offence
Case XCIV
Gaius1. D.13.6.18.1. in the nineth book on the Provincial Edict. obiter dictum. Action on Business Law, a Contract (Affirmation – Cumulative Punitive Actions). Lex Aquilia. liability | |||
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sive autem pignus sive commodata res sive deposita deterior ab eo qui acceperit facta sit, non solum istae sunt actiones, de quibus loquimur, verum etiam legis Aquiliae, sed si qua earum actum fuerit, aliae tolluntur | If an object that has been pledged or loan or deposited is made worse by the person who takes it, not only do those (contract) actions under discussion lie, but also the action under the lex Aquilia. But if suit is brought on any of these actions, the rest are eliminated | ||
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Footnote. | 1 | Gaius, a jurist | |
Aquilian action can be cumulated with a punitive action, such as iniuria, “outrage”
In business law, an action on contract cannot be cumulated. If Aquilian law overlaps a property law claim, the plaintiff forswears the Aquilian action.
Nota bene: See Case XCV, below. A dissenting juristic statement concerning cumulative punitive actions
Case XCV
Paulus1. D.44.7.34.2. in the monograph on Concurrent Actions. obiter dictum. Action on Business Law, a Contract (Dissent – Cumulative Punitive Actions). Lex Aquilia. liability | |||
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…et hoc inlegis Aquiliae actione dicitur, si tibi com-modaverto vestimenta est tuea ruperis, utraeque enim actiones rei persecutionem continen. et quidem post legis Aquiliae actionem utique commodati finietur, post commodati an Aquiliae remaneat in eo, quod in repetitione triginta dierum amplius est, dubitatur, sed verius est remanere, quia simplo accredit et simplo subducto locum non habet | …this is also held with regard to the action under the lex Aquilia, if I lend (commodavero) clothes to you and you rend (ruperis) them, for both actions involve recovery of (compensation for) a thing. Indeed, after an action under the lex Aquilia, that on loan (commodatum) will always be ended. But there is doubt whether, after one on loan, the Aquilian remains for any excess in recovery for the thirty-day period. But the more correct view is that it remains, since it goes beyond the simple value, but it does not lie when the simple value is subtracted | ||
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Footnote. | 1 | Paulus, a jurist | |
Paulus is asserting the action can be either Aquilian or in factum, but not both
The plaintiff can be compensated either in money or an in-kind good. But the plaintiff cannot be compensated twice. The key concept in the obiter dictum is: actiones rei persecutionem, the “recovery of a thing”. In this instance, Roman jurisprudence focuses on recovery or compensation, not a punitive penalty
The Paulian dicta, “utterance” is not within the intent of Aquilian jurisprudence iniuria, “outrage” but is focused on the realty of the forum, the “marketplace”
Conclusion
Roman property law has many complexities, with the basic principle is present: does the property owner have possession, and does he control his holding?
In many instances, as elsewhere in this series concerning Roman jurisprudence, establishing fundamental principles is through actions concerning slaves. Case LXXXII looks as multiple defendants as co-defendants and their cumulative liability. Further along this line of enquiry is noxal liability in LXXXIII where the concern is focused on the paterfamilias and the free born person and personal debt. Other worries the property owner may have include the bonae fidei possessori, the good faith possessor, such that the loanee may incur payable debt
No case is more Roman than the dispute between co-owners of a slave in LXXXVI, the court will not hear the case. Settle the matter between yourselves, for social civility and dignity will be maintained
lex Aquilia, to be actionable in the courts, must be a positive act, that is; the petitor, the plaintiff must suffer a visible harm from the reus, the defendant. Consequently, we look to Iulius Paulus and his obiter dicta
The maturing of Roman case law is exhibited by two obiter dicta contributed by Paulus, a jurist during the reign of Marcus Aurelius Antoninus, better known by his nickname as Caracalla, from 198 to 217 CE, the late Classical era, from 190 to 235 CE
Paulus wrote dissenting comment in cases XCIII and XCV, to XCII and XCIV respectively. The salient point is that old, or better phrased, “former” concepts of jurisprudence, are challenged. Jurisprudence matures and evolves as the society it supports too matures and evolves
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expressum facit cessare tacitum
When there is express mention of certain things, then anything not mentioned is excluded
Said of those who do not thoroughly prepare their arguments
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