Ius means

The law. Ius is often contrasted with lex or leges, which are the laws. Ius is the law in its broadest sense or ideal state. It is above and largely unaffected by the contingent statutes or other laws that the state happens to enact, which are the leges. From this difference arise the English terms “justice” and “legislation.” This division remains common in civil law through various terms and is continued in the law of the United States, as in the Fourteenth Amendment of the United States Constitution, which distinguishes “due process of law” as in ius from “equal protection of the laws” as in leges.

Ius abutendi

One of the attributes of dominium, or ownership, usually conceived of as the right or power to consume a thing owned, if it is capable of consumption. Pound uses it to illustrate the sense of dominium that corresponds to liberty in the sense of an immunity from interference by others under the law, as opposed to a power or a right.

Ius ciuile (civile)

In Roman law, the laws that resulted from statutes and decrees governing the citizenry, particularly as elaborated by the commentators of Roman law. Pound is particularly concerned with the distinction between ius civile and ius gentium employed by Gaius, according to which the ius civile is the law that applied only to Roman citizens and not between foreigners or between Romans and foreigners, who were governed by the ius gentium.

Ius disponendi

One of the attributes of dominium, or ownership, usually conceived of as the right or power to dispose of a thing owned. Pound uses it to illustrate the sense of dominium that corresponds to liberty in the sense of an immunity from interference by others under the law, as opposed to a power or a right.
Ius fruendi. Another of the attributes of dominium, or ownership, in that one who has dominium has the right or power to reap fruits or profits, as by harvesting crops or taking rents from the property. Pound uses it to illustrate the sense of dominium that corresponds to liberty in the sense of an immunity from interference by others under the law, as opposed to a power or a right.

Ius gentium

This term had a variety of meanings. In early Roman law, it is the law that is followed by all peoples, and so it is closely akin to the ius naturale. From this universal sense, it was also used more specifically to describe the international law that governed Rome’s relationship with other states. Following the works of Gaius, the term was employed more narrowly to represent the law that applied between foreigners and between Romans and foreigners. Foreigners, and the legal relations of Romans with them, were governed by the ius gentium.

Ius naturae

Literally, “the law of nature.” In Roman law, very nearly a synonym for ius naturale; it is a law that is supported by natural reason, and so it is a law that is, or ought to be, respected by the laws of all nations. Thus, the ius naturae was said to support the ius gentium in its universal sense, but even this relationship is not always congruent: famously, in the introduction to Justinian’s Institutes, slavery is forbidden by nature but allowed by the ius gentium. Even so, there was the general sense, seized on increasingly from Roman writings throughout the Renaissance and early modern age, that the object of civil law was to reflect the obligations of natural law, especially when natural law required freedom.
Ius naturale or, as the Roman jurist Ulpian said, “that which nature taught all animals.” For most writings of classical Roman law, it is synonymous with ius naturae. From the writings of Paul, however, the term ius naturale acquired the sense of an ideal of law, quod semper est bonum et aequum, or that which is always fair and just. It is this sense that is followed in the Thomist conceptions of natural law, or lex naturalis.

Ius possidendi

One of the attributes of dominium, or ownership, in that one who has dominium has the right or power to possess the property. Pound uses it to illustrate the sense of dominium that corresponds to liberty in the sense of a right against all others to act to make the interest effective or to forbear from interfering.

Ius prohibendi

Another of the attributes of dominium, or ownership, in that one who has dominium has the right or power to prohibit others from using the property, whether by possession alone or by growing or harvesting crops or using or taking rents from the property. Pound uses it to illustrate the sense of dominium that corresponds to liberty in the sense of a right against all others to act to make the interest effective or to forbear from interfering.

Ius strictum

A very rare term in the materials of classical Roman law, ius strictum, or the strict law, is really a Byzantine term, and it occurs in Justinian’s Institutes in reference to the strict actions of the law, primarily to describe the rigid limitations of the forms of action available under the law, particularly the older laws. The term is often used by later commentators, as it is here by both Jhering and Pound, to distinguish it from the moderating influence of the praetors, or judges who expanded the law through actions ex fide bona, or what we would now call equity.

Ius utendi.

Another of the attributes of dominium, or ownership, in that one who has dominium has the right or power to use the property, particularly by residing there. Pound uses it to illustrate the sense of dominium that corresponds to liberty in the sense of an immunity from interference by others under the law, as opposed to a power or a right.


Source: Roscoe Pound, The Ideal Element in Law [1958]