Chapter V: Relation of Natural Law to General Customary Law

There are, however, misconceptions against which we must be on our guard in grasping and appraising this identification of Natural Law with the sum of that which is common in the customs of mankind.

In the first place it was not a complete identification. There were some points in which Natural Law and the Law of the Nations differed, and one of these was of profound importance. That point was Slavery. It was universal in the ancient world, and so must be deemed a part of _ius gentium_. But philosophers had pointed out (even before the time of Cicero) that it was contrary to nature[59]. Here, therefore, is a large department in which the sanction of Nature could not be claimed for this part of _ius gentium_ any more than it could for much of _ius civile_. Slavery, says one jurist, is an institution of the Law of the Nations, whereby one man is subjected to the ownership of another against Nature[60]. And where we find the rigour of the old law of Slavery modified, this is always said to be in deference to nature and humanity, not to anything in _ius gentium_. And the Roman jurists indeed go so far as to hold that by Nature all men are equal[61]. So on the other side there were some provisions of statute law (for instance, in the rules regarding inheritance) which, though they had been suggested by principles ascribable to the Law of Nature, were, as resting on Roman statutes, referred to the category of _ius civile_ rather than to that of _ius gentium_.

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Footnote 59:

Ulpian in _Dig._ l. 17. 32.

Footnote 60:

_Dig._ i. 5. 4, § 1: cf. _Inst._ i. 5; Gaius, _Inst._ i. 52.

Footnote 61:

The doctrine that slavery is against nature was older than Aristotle,
who does not accept it. The orator Alcidamas (a contemporary of
Socrates) said ἐλευθέρους ἀφῆκε πάντας θεός· οὐδένα δοῦλον ἡ φύσις
πεποίηκεν. See W. L. Newman’s _Politics of Aristotle_, Introduction,
p. 141.

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Secondly, the Romans did not, when they referred any particular institution to the _ius gentium_, necessarily intend to convey that it was universally prevalent. The origin of _hypotheca_ for instance (mortgage of immovables) and of the _syngraphe_ (written acknowledgement of a debt) was due to Greek usage, and by no means general over the world. These legal institutions, however, since they did not belong to Roman law proper, were held to be part of _ius gentium_.

Thirdly, there is no ground for thinking that when the Roman jurists said that Natural Reason was the source of _ius gentium_, they had altered their historical view of the origin and character of the latter body of law, or fancied that there ever had been an age, however remote, however simple and primitive, during which its precepts, in any concrete shape they knew or could imagine, had actually prevailed among mankind. The expression ‘lost Code of Nature,’ which a distinguished writer has used[62], is therefore an unfortunate one, for it seems to imply that the Romans were under the belief that there had once been a so-called State of Nature, in which the _ius gentium_ served as law. So far were they from such a delusion that they ascribe to _ius gentium_ war, captivity, slavery, and all the consequences of these facts, while in the golden age, the _Saturnia regna_ of the poets, all men were free[63] and war was unknown—

‘Necdum etiam audierant inflari classica, necdum
Impositos duris crepitare incudibus enses[64].’

Their identification of the Law of Nature, which they accepted as a doctrine of philosophy, with the Law of Nations, which their courts had been administering and their text-writers expounding for two or three centuries at least, affected neither the essentially ideal character of the former nor the distinctly practical character of the latter. Had it done either of these things it might have worked for evil. But in point of fact it did not palpably quicken the pace of legal reform, nor did it induce any theoretic vagueness in their views of law, or suggest crochets or subtleties which could impede the manipulation of positive rules. The jurists use the two terms as practically synonymous, though generally employing _ius naturae_ or _naturalis ratio_ when they wish to lay stress on the motive or ground of a rule,_ius gentium_ when they are thinking of it in its practical application. To borrow the language of logic, the connotation of the two terms is different, while their denotation (save as aforesaid, and especially save as regards slavery) is the same.

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Footnote 62:

Sir H. Maine in _Ancient Law_. It will be seen that the view which he
takes of _ius gentium_ and _ius naturae_ seems to me to be in several
points at variance with the facts; but I need hardly say that no one
feels more strongly than I do the value of the stimulus to English
study and thought on these subjects which his fertile mind and
brilliant treatment have given, and for which all subsequent writers
must be grateful.

Footnote 63:

Cf. Macrob. _Saturn._ i. 7; and Justin. _Hist._ xliii. 1, who says
that not only slavery but also private property was unknown under the
reign of Saturn, so great was his justice!

Footnote 64:

Virg. _Georg._ ii. 539.

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Thus happily united by a synthesis which satisfied at once the practical good sense and the philosophic temper of the Roman jurists, the two conceptions of the Law of Nature and the Common Law of Mankind went on their way rejoicing. But after a while an event befell which deprived the latter expression of its ancient concrete basis, and rendered it, except for historical purposes, and as a description of a body of rules of a particular historical origin, virtually obsolete. This was the extension of Roman citizenship to all the subjects of the Roman Empire by an edict of the Emperor Antoninus Caracalla between 212 and 217 A.D., an act which destroyed the distinction between _ius gentium_ and _ius civile_ so far as the persons governed by each were concerned, for there were thereafter comparatively few _peregrini_ (non-citizen subjects), since _ius civile_ was now enjoyed by all the dwellers in the Roman world[65].

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Footnote 65:

There remained as aliens (1) the class called _dediticii_, the lowest
species of freedmen, (2) persons deprived of citizenship as a
punishment for crime, (3) foreigners, _i.e._ subjects of some other
State temporarily resident in the Empire, and probably also persons
imperfectly manumitted subsequently to the Edict, together (possibly)
with the inhabitants of territories added to the Empire subsequently
to the Edict. See Muirhead (_Historical Introduction to the Private
Law of Rome_, 2nd edition, by Professor Goudy, p. 319), and, for a
fuller discussion of the topic, Mitteis, _Reichsrecht und Volksrecht
in den östlichen Provinzen des Römischen Kaiserreichs_, chap. vi.

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This may be one of the reasons why, in the constitutions of the Emperors collected in the Codes of Theodosius the Second (A.D. 438) and of Justinian (A.D. 534), constitutions the earliest of which date from Hadrian, the term _ius gentium_ never occurs. It is frequent in the _Institutes_ of Justinian (A.D. 533), but that book (based on the _Institutes_ of Gaius) is, although a statute, yet primarily a manual for learners who were going to use the extracts from old jurists contained in the Digest, so that the term could not be omitted. When the later Emperors wish to assign a ground for some enactment which they are issuing, they commonly speak of Nature, or Natural Reason, or Humanity, or Equity, using these words almost indiscriminately to describe the same thing.