Ius - G

Jus gentium. The law of nations. That law that natural reason has established among all men and which is equally observed among all nations is called the law of nations, "as being the law that all nations use". Inst 1, 2, 1; Dig. 1, 1, 9; 1 Bl. Comm. 43; 1 Kent, Comm. 7; Mackeld. Rom. Law, § 125.

Although this phrase had a meaning in Roman law that may be rendered by our expression "law of nations," it must not be understood as equivalent to what we now call "international law," its scope being much wider. It was originally a system of law, or more properly, equity, gathered by early Roman lawyers and magistrates from the common ingredients in the customs of the old Italian tribes—those being the nations, gentes, whom they had opportunities of observing—to be used in cases where the jus civile did not apply; that is, in cases between foreigners, or between a Roman citizen and a foreigner. The principle upon which they proceeded was that any rule of law common to all the nations they knew of must be intrinsically consonant to right reason, and therefore fundamentally valid and just. From this it was an easy transition to the converse principle, viz., that any rule that instinctively commended itself to their sense of justice and reason must be a part of the jus gentium. And so the latter term came eventually to be synonymous with "equity" (as the Romans understood it.) or the system of praetorian law.

Modern jurists frequently employ the term ius gentium privatum to denote private international law, or that subject that is otherwise styled the "conflict of laws"; and ius gentium publicum for public international law, or the system of rules governing the intercourse of nations with each other as persons.

Ius gentium. In early Roman law, the law followed by all peoples, closely akin to the ius naturale. From this universal sense it was 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 among foreigners, and among Romans and foreigners. Foreigners, and the legal relations of Romans with them, were governed by the ius gentium.

Ius gladii. The right of the sword; the executory power of the law; the right, power, or prerogative of punishing for crime. 4 Bl. Comm. 177.