The Romans were thoroughly familiar with the
ideas about law which enter into the tradition of constitutionalism, even
though these ideas played no important part in their public life. At least in
the late formulations, the generality of law was taken for granted: Law
(lex) is a general precept, said Papinian;1 and Ulpian wrote,
"Laws (jura) are not established for individuals, but for general
purposes."2 Prospectivity was likewise assumed, and occasionally
this assumption was made explicit. An explosive passage in Cicero seems to
argue that a retroactive measure is a physical impossibility.3 The
Theodosian Code states that laws do not condemn past actions but fix a rule for
the future,4 and the Code of Justinian preserves a command by
Theodosius II and Valentinian III that laws are not to be applied to past
transactions unless they are expressly made retroactive.5
But if jus and lex were general, special laws were familiar enough. The
earliest name for these measures was privilegia. The privilegium
was, as the name indicates, a private law, a piece of legislation dealing only
with individuals or with particular groups. Ordinarily it conferred a benefit
or immunity. In 450 b.c. the Twelve Tables forbade the passing of
privilegia "in favor of private persons to the injury of others,
contrary to the law common to all citizens, and which individuals, no matter of
what rank, have a right to make use of."6 Cicero in 57 b.c. appealed
to this provision of the Twelve Tables in order to secure the return of his
home, which had been consecrated during his exile by Clodius.7 It is
not clear that a special measure which conferred no privilege but merely
operated to the disadvantage of a single person came within the prohibition of
the Twelve Tables, but in the Laws also Cicero defined a
privilegium as a law which penalized a particular
After Cicero there were no protests against privilegia. Aulus Gellius in
the second century after Christ defined lex as a general command, a
privilegium as one concerning individuals.9Privilegia
constituted a great part of the jus singulare; the remainder consisted
of rules special in the sense that they deviated from the general tenor of the
law. Opposed to jus singulare was jus commune, the general
law.10 Paulus in the third century wrote a Liber singularis de
jure singulari, of which nothing survives but the definition, "Special law
is that which has been introduced by the authority of those establishing it
against the tenor of a legal principle, on account of some particular
Justinian's Code contains many examples of privilegia: those of the
cities of Rome and Constantinople12 and of metropolitan
cities;13 of the corporate bodies of Rome;14 of persons
employed in the imperial palace,15 and those serving in favored
divisions of the army;16 of the Fiscus;17 and of
the lands of the emperor.18 The action for dowry is called
privilegium dotis.19 Such privileges, since they did no
immediate injury to anyone, did not appear inequitable. They were not given
application beyond the particular cases for which they were
The position of the emperor raised a problem somewhat analogous to that
of the privilegium. The emperor was, as Ulpian said, legibus
solutus, exempt from the operation of the law, and he ordinarily conferred
the same privilege upon the empress.21 But it was not considered
proper for the emperor to avail himself of this immunity to the disadvantage of
subjects; it was "dishonorable," said Paulus, and unworthy of his majesty not
to submit to the laws.22 The authors of panegyrics to the emperors
praised them for their obedience to law.23 This opinion culminated
in the famous digna vox declaration of Theodosius II and Valentinian III
in the year 429: "It is a statement worthy of the majesty of a reigning prince
for him to profess to be subject to the laws; for our authority is dependent
upon that of the law. And, indeed, it is the greatest attribute of imperial
power for the sovereign to be subject to the laws, and we forbid to others what
we do not suffer ourselves to do by the terms of the present
This constitutional morality, as it might be called, developed in
connection with two problems in the law. The first arose in the law of wills.
It was not uncommon for testators to make the emperor their heir in order to
secure to their estates litigious claims or to make good some deficiency in the
will. Pertinax refused to accept such inheritances, and Severus and Antoninus
likewise declared: "Although we are above the laws, yet we live in obedience to
them."25 Hadrian wrote, "It has frequently been decided that even
the emperor cannot claim an estate under an imperfect will, for although the
lex imperii has released the emperor from the formalities of law,
nevertheless nothing is so fitting to sovereignty as to live according to the
laws."26 Even more important in establishing the conception of the
rule of law was the constitutional position of the Fiscus. This was the
imperial treasury, which first overshadowed and then swallowed up the
Aerarium, the popular treasury surviving from the republic. It was the
creditor or debtor in all claims by or against the state. It could sue and also
could be sued. It was in many cases subject to the rules of private law, in
others to rules peculiar to the Fiscus, but in all cases to known and
settled rules.27 So Roman law developed the doctrine of the
suability of the sovereign which has been in modern times the envy of English
and the boast of German jurisprudence.
In the sixteenth century Jean Bodin offered in his Six Books of the
Republic what is usually called the first statement of the doctrine of
sovereignty. Law is the will of the sovereign, and sovereignty is the capacity
to make law by an act of will. But the sovereign is limited in four ways: he
must observe the laws of God and nature; he cannot alter the "laws which
concern the state of the realm, and the establishing thereof"; he must respect
the property of his subjects; and he must honor his contracts. The first
limitation came from medieval ideas rather than Roman law, for the Roman
jurists were clear that any imperial command, however unreasonable, was
law.28 The second referred to certain French laws, such as that
governing succession to the throne, which the king could not alter. The third
also had a medieval background, although Seneca had distinguished between
imperium and dominium.29 The fourth was, perhaps,
drawn from the Roman law.
(1) Digest, I, 3, 1.
(2) Digest, I, 3, 8, in Samuel P. Scott, trans.,
The Civil Law (Cincinnati, 1932), ii, 223.
(3) De domo sua, XVIII.
(4) I, 1, 3.
(5) I, 14, 7.
(6) Table IX, Law I, in S. P. Scott, op. cit., i,
(7) Op. cit., XVII.
(8) Laws, III, 44.
(9) Attic Nights, X, 20.
(10) Carl Salkowski, Institutes and History of Roman
Private Law (E. E. Whitfield, trans.: London, 1886), pp. 14-15.
(11) Digest, I, 3, 16, in S. P. Scott, op.
cit., ii, 224. See also Modestinus, Digest, L, 17, 196.
(12) Code, XII, 21 (20).
(13) Ibid., XII, 22 (21).
(14) Ibid., XI, 15 (14).
(15) Ibid., XII, 28 (29).
(16) Ibid., XII, 29 (30).
(17) Ibid., VII, 73.
(18) Ibid., XI, 75 (74).
(19) Ibid., VII, 74.
(20) Institutes, I, 2, 6; Code, I, 6,
(21) Digest, I, 3, 31.
(22) Digest, XXXII, i, 23.
(23) Lester K. Born, "The Perfect Prince according to
the Latin Panegyrists," American Journal of Philology (1934), lv, 20;
Mason Hammond, "Pliny the Younger's Views on Government," Harvard Studies in
Classical Philology (1938), xlix, 115.
(24) Code, I, 14, 4, in S. P. Scott, op.
cit., xii, 86-87.
(25) Institutes, II, 17, 8 (Thomas C. Sanders,
trans.: Chicago, 1876), p. 283. See J. B. Moyle, Imperatoris lustiniani
Institutionum (Oxford, 1912), p. 2790.: "For acceptance under informal
wills by the Emperors cf. Suetonius, Calig. 38, Domit. 12, Pliny, Paneg.