Uti possidetis is an expression that originated in Roman private law, where it was the name of a procedure about possession of land. Later, by a misleading analogy, it was transferred to international law, where it has had more than one meaning, all concerning sovereign right to territory.
In Rome, if two parties disputed possession of a house or parcel of land, the praetor preferred the one who was in actual occupation, unless he had got it from the other by force, stealth or as a temporary favour (nec vi, nec clam, nec precario). The contest was initiated by an interdict called . The winner was confirmed or restored in possession, and the loser was ordered not to displace him by force. However, the winner had not proved he was the real owner, only that, for the moment, he had a better right to possession than his opponent. Hence the rights of third parties were not prejudiced. The phrase uti possidetis was a conventional abbreviation of the praetorial edict dealing with such matters.
In the early modern era, some European states, when dealing with other European states, used the phrase to justify the acquisition of territory by occupation. There was no universally agreed rule and, for example, Portugal applied it more ambitiously than Spain. Despite that, there is no doubt that important polities, such as Brazil, were established on that interpretation. It was also a generally accepted rule about the interpretation of peace treaties. A peace treaty was presumed to give each party a permanent right to the territory it occupied at the conclusion of hostilities, unless the contrary was expressly stipulated. Whether this rule has survived in the international regime following the creation of the United Nations must be doubtful. This usage is sometimes called uti possidetis de facto.
In recent times, uti possidetis refers to a doctrine for drawing international boundaries. When colonial territories achieve independence, or when a polity breaks up (e.g., Yugoslavia), then, in default of a better rule, the old administrative boundaries between the new states ought to be followed. This doctrine, which has its critics, is sometimes called .
Roman law
Introduction A displaced landowner who wanted to recover his property could bring a traditional action called , which was theoretically a simple procedure. All he had to do was to prove he was the owner and the defendant was in possession. But in reality proof of ownership could be exceedingly difficult for lack of documentation since, during the formative period of Roman law, there was no system of written conveyancing and registration of land. In the Republican era most land transfers were verbal and did not even have to be witnessed. Consequently, as time went by, there must have been many Roman estates whose owners could not prove they were.
Accordingly, in litigation about land each party tried to manoeuvre a situation where the burden of proof was cast on his opponent, and he merely had to defend."And as it is far more advantageous to possess than to claim the possession; there is generally, indeed, nearly always, a great effort made to obtain the possession. The advantage of possessing consists in this, that even though the thing be not his who possesses it, yet if the plaintiff cannot prove that it is his, the possession remains where it is. and, for this reason, when the rights of both parties are doubtful, it is usual to decide against the claimant." JUST. IV, xv, §5 (). To achieve this they went outside the traditional Roman actions and used a praetorial remedy.
Praetorial remedies Already in the Roman republic the praetor was an official whose duties included the keeping of the peace. A praetor held office for a year, at the start of which it was customary for him to publish edicts; these announced the legal policies he intended to apply. Usually they were adopted with or without modification by his successors. With these edicts praetors could change the law, though they did it somewhat cautiously.
An interdict was a praetorial order forbidding someone to do something. The one relevant for present purposes was the interdictum uti possidetis. It seems this interdict was available by about 169 B.C. because there is a joke about it in one of Terence's comedies, though we do not know the praetor's original wording. Probably it originated as a means of protecting occupants of public lands, since these people if expelled could not have sued as owners. Later, however, it was adapted as a procedural device to assign disputants to the role of plaintiff and defendant, respectively.
The interdict uti possidetis The law was summarised by the Roman jurist Gaius (Institutes, Fourth Commentary), as follows:
+ Latin textSource: Krueger and Studemund's apograph of the Verona palimpsest of Gaius' Institutes as reproduced in English translation Interdicts for retaining possession are regularly granted when two parties are disputing about the ownership of a thing, and the question which has to be determined in the first place is which of the litigants shall be plaintiff and which defendant in the vindication*; it is for this purpose that the interdicta Uti possidetis and Utrubi have been established. The former interdict is granted in respect of the possession of land and houses, the latter in respect of the possession of movables. When the interdict relates to land or houses, the praetor prefers the party who at the issuing of the interdict is in actual possession, such possession not having been obtained from the opposing party either by violence or clandestinely, or by his permission. When the interdict relates to a movable, he prefers the party who in respect of the adversary has possessed without violence, clandestinity, or permission, during the greater part of that year. The terms of the interdicts sufficiently show this distinction. *The vindication was the name of the traditional action for claiming ownership of land, as already explained.
A person could establish possession by occupying the property himself, or through another e.g. his inquilinus (house tenant) or colonus (agricultural tenant).
The three exceptions: nec vi nec clam nec precario That the praetor would confirm the party in possession was only a default rule, since there were three exceptions: Vi (force). If the possessing party had got it from the otherMaybe he had got it by force from a third party; but if he was not before the praetor complaining, it was of no present concern. by force he was not entitled to the benefit of the interdict. Otherwise it would reward the getting of land by violence. Clam (stealth). Likewise if his possession had been obtained furtively; and for a similar reason. Precario. A precario was a person who was in possession only by favour, and could be told to leave at any time. (Hence the English word precarious.)
If any of those exceptions applied his possession was flawed (this was called possessio vitiosa) and did not count.
Third parties If he had got his possession from a third party, though, it did not matter that he had done it illegitimately, i.e. it was of no present relevance. This is made explicitly clear by Justinian's Institutes, IV, XV §5: It was up to the third party to initiate legal proceedings about that, if he wanted to; he was not shut out.
This was significant when early modern European powers sought to apply the uti possidetis concept to their colonial acquisitions (see below). Thus, that they had vanquished the indigenous inhabitants by force was of no present consequence if a dispute was between rival Europeans.
Procedure
On the first appearance in court the praetor, whose time was valuable, did not try to investigate the facts. He simply pronounced the interdict impartially against both parties. (Hence it was called a "double interdict").So called, wrote Gaius, "because the footing of both parties is equal, neither being exclusively plaintiff or defendant, but both playing both parts, and both being addressed by the praetor in identical terms." (.) Conceivably, one of the parties knew he was in the wrong and decided he had better obey the praetor's interdict. If so, that was the end of the matter. Suppose, however, he chose to brazen it out or, indeed, sincerely believed himself to be in the right.
The next step was to bring matters to a head. Accordingly, on a prearranged day the parties would commit a symbolic act of violence (vis ex conventu) e.g. pretending to expel each other from the land. That, for the one in the wrong, must have been a formal disobedience of the praetor's order. Each party now challenged the other to a wager by which he had to pay his adversary a sum of money if it was he who had disobeyed the interdict. (This way of settling disputes in Rome — by having a wager on the result — was called agere per sponsione). The agere per sponsonie was sent off to be tried by a iudex (akin to a one-man jury, usually a prominent citizen), who in due course delivered his decision. Meanwhile, the right to interim possession of the land was auctioned to whichever of the two contestants was the highest bidder, on his promise to pay his adversary the rent if he turned out to be in the wrong.
Roman litigation was not for the faint-hearted. Getting one's opponent into court at all could be difficult, and arguably praetors "were nothing more than politicians, frequently incompetent, open to bribery, and largely insulated against suits for malfeasance". A litigant could frustrate the interdict process by omitting to take part in its rituals. When that happened, however, it was possible to obtain a secondary interdict by which he lost the case at once.
Advantages of the interdict Although the interdict neither conferred nor recognised any proprietary right, the party who prevailed had achieved three important advantages.
First, he enjoyed peaceful possession of the land against his adversary for the time being. Secondly, although his opponent might yet get the land — by bringing a vindicatio — the case had to be proved. This was important since it assigned the burden of proof. Thirdly, and in practice, his opponent might not trouble to take it further. Then, the party left in possession looked very like the real owner. As time went by it must have become more and more difficult to prove he was not.
In sum, by peaceful, open and unlicensed possession of land a party did not acquire ownership, but he did acquire practical advantages.
The Roman doctrine about establishing possession (not ownership) may seem slightly elusive for those brought up in the Anglophone common law where it is trivially obvious that a good title to land can indeed be acquired by mere occupation (e.g. "squatters' rights"). However, it was not so in Roman law which drew a sharp line between ownership and possession. Except in special cases, mere occupation of land could not confer ownership.
Later knowledge: the text of the edict Although Gaius' text was imperfectly known to early modern Europeans, because it was lost and not rediscovered until 1816, they knew the edict in the later recension by Justinian. The interdict's name uti possidetis was a conventional abbreviation of the wording of the praetorial edict:
which has been translated
Much later, when it came to be adopted in international law the abbreviation was represented as Uti possidetis, ita possideatis ("as you possess, so may you possess"), whereby "possession became ten-tenths of the law", said to be a perversion of the Roman doctrine.
Uti possidetis as a doctrine for the acquisition of territory in international law From Roman private law, uti possidetis was transposed to international law as an assertion of sovereignty over territory, although the analogy was misleading.