[Primary references: Henry Maine, Ancient Law, H.S.M., January, 1861; John Crook, Law and Life of Rome, Cornell University Press, c1967; Will Durant. The Story of Civilization, Part III, Caesar and Christ, A history of Roman Civilization and Christianity from their beginnings to AD 325, Simon and Schuster, NY, c1944..]

Usucapion acted as a self-correcting mechanism until law and equity became fused under the various codes. Mancipation was discontinued as the form of conveying res mancipi with the reforms of Justinian. At that time, the period of equitable possession adverse to the owner under title in law was lengthened and the mechanism evolved into "prescription."

The historical origin of "adverse possession" stemmed from the fact that the Patrician burghers of Rome became major tenants of the greatest part of the ager publicus (public lands) at nominal rents. Under old Roman law, they were mere "possessores" without legal title through mancipation. They were not "domini," but they were possessors intending to keep their land against all comers. They put forward a claim admitting that although they were theoretically the tenants-at-will of the state, time and undisturbed enjoyment had ripened their holding into a species of ownership, (prescription,) and that it would be unjust to eject them for the purpose of redistributing the lands under various land schemes.

If threatened with disturbance or "ejection" from their possession, the only remedies available to these Patrician tenants were the Possessory Interdicts - ordinances of the Roman Praetor that enjoined or forbade dispossession or ejection pending the settlement of questions of legal right.

A series of attempts at agricultural reform under the Lex Agria, (law on agriculture,) proposed allowing the patricians clear title to a portion of the land they held as tenants, with the remainder reverting to the imperium for redistribution to the urban poor. In addition, municipalities with large corporate holdings of ager publicus began the practice of letting out agri vectigules - leasing land for a perpetuity to a free tenant, at a fixed rent (tenure), and under certain conditions. Such "emphyteusis," (implanting,) was afterwards extensively imitated by individual large landholder proprietors, encouraged by the policies of Hadrian. The free tenant, whose relation to the owner had originally been determined by his contract, was subsequently recognized by the Praetor as having himself a qualified proprietorship or equitable possessory ownership through tenure.

It came to be generally understood that everybody who possessed property as his own also had the power of demanding the Interdicts. The complex formalities of the Real Action in Law as a remedy for recovery of real property eventually became discarded in favor of the simpler possessory actions of "ejectment." By a system of highly artificial pleading based upon the "legal fiction" that possession was inherent in ownership by title, the Interdictal process was manipulated to serve in trials in equity of conflicting claims to a disputed possession. These became guided in both Roman and English law by applicable Maxims. Ejectment became used by both possessors and owners to convey the right to use land when the title in law was held by the state, monarch.or lord.

Henry Maine references the German jurist Savigny as declaring that in later Roman Law, all property became founded on adverse possession (a holding not permissive or subordinate, but exclusive against the world,) ripened by prescription, (a period of time during which the adverse possession has uninterruptedly continued.)

Through William the Conqueror, Saxon manorial land holding became overlain with the feudal concept of "sovereign title and dominion" - the superior absolute exclusive right of use (ownership) of the country's land and resources perpetually vested in the monarch in the manner of the Roman pater familias . Direct grants of land made by the monarch to others were held in conditional "fee" title (feud or fief.) These were further subinfeudated to others. "Possessory" title or equitable title was later employed to alienate or sell use without feudal obligations, leaving a naked "fee" title and feudal obligations in the original grantee. Eventually, this created a situation somewhat similar to the tenants of the ager publicus where sovereign title, "fee" title and actual possession were mired in complexities. "Ejectment" eventually became the common mode of transference of interest in lands under English Law.

The principles of possessory ownership survived, as explained in Roger Bernhardt's Real Property in a Nut Shell, Third Edition, West Publishing, c1993; and came to play a fundamental role in the acquisition of property in America's western lands:

From this doctrine arose the maxim "possession is nine points of the law."

Ejectment became relegated to matters of hostile acquisition as regards trespass upon privately owned property:

[From Roger Bernhardt's Real Property in a Nut Shell, Third Edition, West Publishing, c1993.]