by some individuals, apparently for plausible reasons. Such, indeed, was the opinion upheld by Augustine (Against Faustus, Bk. XXII, chaps. [lxxiv and] lxxv), and quoted in the Decretum (Pt. II, causa XXIII, qu. i, can. iv).
The question, indeed, of the degree of certitude—regarding this injustice in a law—that is necessary in order to oblige men not to obey that law, is repeatedly dealt with in comments on I.–II [, qu. 96, art. 4],
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on conscience. Furthermore, we shall make some comments on this same point below,21 when we discuss the binding force of law, and especially that of human law. For doubts of the kind in question are particularly wont to occur with respect to law of this sort [i.e. human law], and they may take many diverse forms; so that this subject will be disposed of more fittingly and more fully in that [later] context. On the other hand, the question of how in a doubtful case a presumption is made in favour of the prince, is treated at length by Panormitanus (on Decretals, Bk. I, tit. II, chap. vii, no. 14), Felinus (ibid., nos. 60 et seq.) and Torquemada (on Decretum, Pt. II, causa XI, qu. iii, can. i, concls. 6 and 7, nos. 8 and 9, and ibid., can. xciii, at end).
12.22 The second assertion: it is inherent in the nature of law that it be justly established. My second assertion is as follows: it is inherent in the nature of law, that it be justly established; and if it is established in any other way, it will not be true law. The first part of this assertion is commonly accepted as true. Moreover, since in the case of divine laws it is a quite self-evident fact that they are justly established, it is in regard to human laws that we shall explain this assertion; which St. Thomas [also] has set forth in the question above cited (I.–II, qu. 96, art. 4). All the commentators on this passage, and others, to be cited presently, [agree on this point].
The said assertion, however, finds a first and general proof in the fact that conformity with reason is inherent in the nature of law, a fact proved by all the arguments adduced just above and acknowledged, moreover, by all the philosophers there cited; but in order that law may be in conformity with reason, it is not enough that the subject-matter of law should be righteous; on the contrary, its form must also be just and reasonable, which is to say that law must be established in a just manner; therefore, this latter requirement is likewise essential to the nature of law.
A second and specific argument is based upon the supposition that, when we declare establishment in a just manner to be inherent in the nature of law, we refer to a just mode of operation, not as regards the [legislative] agent, but as regards the product of his efforts. For, with respect to the mode
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of operation in its relation to the agent, it is necessary, not only that there be no defect in the law itself, but also that the agent be moved by a virtuous impulse, not by hatred or cupidity, and that for his part he conduct himself prudently in regard to the mode and circumstances of his action. But this good or virtuous behaviour on the part of the legislator who makes a given law, is not necessary to the validity of the law. For a prince may conduct himself wickedly and unjustly when he makes a law, while the law which he makes may nevertheless be just and good, and also valid. With respect to the law itself, however, the requisite mode involves not only righteousness in the subject-matter of the law, but also righteousness in its form. A law, then, is said to be just when the form of justice is preserved in it, a point which St. Thomas (ibid., art. 4 and qu. 95, art. 3) neatly expounds.
13.23 Three phases of justice must be observed in order that a law may be made justly. A fuller explanation may be offered, as set forth below. For in order that a law may be made justly, three phases of justice must be perceptible in its form.
The first phase is legal justice. It is the function of this form of justice to seek the common good and, consequently, to guard the due rights of the community; but law ought to be directed chiefly to this purpose, as we have shown; and therefore, law should be made in a just manner from the standpoint of legal justice. Thus it is that St. Thomas (ibid.) declares that law should be just in having as its goal the common good.
The second phase is commutative justice. It is the care of this phase of justice that the legislator shall not exceed his own power in laying down his commands. Such justice is in the highest degree essential for the validity of a law. Consequently, if a prince legislates for persons who are not subject to him, he sins against commutative justice in so far as those persons are concerned, even though he may be requiring an act that is in itself righteous and advantageous. And accordingly, St. Thomas has said that in a law justice on the part of the legislator is a requisite.
The third phase of justice is distributive. This also is a requisite of law. For in the process of laying down commands for the multitude, [law] distributes the burden, as it were, among the various parts of the state,
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for the good of the latter, and must therefore preserve in that distribution a proportionate equality, which is a matter pertaining to distributive justice. Accordingly, a law which apportions burdens unequally will be unjust, even if the thing which it prescribes is not inequitable. It is in this sense that St. Thomas (ibid.) has asserted that a proportionate equality is required in the form of a just law.
From the foregoing, moreover, he correctly concludes that, in addition to its inequity from the standpoint of subject-matter, a law can be unjust in three ways, namely: because the end in view is private advantage, not the public good; or, because of a defect in power on the part of the [legislative] agent; or, because of a defect in the form [of the law], that is, a defect of just distribution.
It is clear, then, that just enactment from all the standpoints above mentioned is essential to law.
14.24 Proof that justice is necessary to the validity of a law. Moreover, the second part of our assertion25—namely, that this justice [in enactment] is so necessary to law that without it law is invalid and ceases to bind—is expressly upheld by St. Thomas in the same place [I.–II, qu. 96, art. 4]; by Soto [De Iustitia et Iure, Bk. I, qu. v, art. iii], B. Medina and others (on that passage of St. Thomas); by Castro (De Potestate Legis Poenalis, Bk. I, chap. v), Victoria (Relectio: De Potestate Papae et Concil., no. 18), Panormitanus (on Decretals, Bk. I, tit. II, chap. vii, no. 9), Felinus (ibid., nos. 40 and 41) and others. This view is also favoured by the Digest (I. i. 1); and the interpreters of that passage may be consulted. St. Thomas, too, interprets as referring to this phase of justice, the words of Augustine above cited (On Free Will, Bk. I, chap. v): ‘That is not law which is not just.’ Still more pertinent to this point is the remark which he makes in the City of God (Bk. XIX, chap. xxi): ‘What is done according to law (iure) is done justly (iuste), and what is unjustly done, cannot be done according to law. For the unjust decrees of men should not be thought of or spoken of as laws, since even they themselves define law as that which has flowed from the fount of justice.’26
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15.27 Finally, it is in this sense that we shall rightly interpret the second condition of law laid down by Isidore in the last of the passages above cited. For he says that ‘law should be righteous and just’; and the first of these attributes relates to the subject-matter of law, as I have pointed out in a preceding statement; so that the second relates to the form of the law, as it were—that is to say, [it implies] that [law] must be justly enacted.
Moreover, this part of our discussion may be demonstrated by reasoning, if we shape our argument in accordance with the three standpoints regarding justice which were indicated by St. Thomas as follows: the end, the [legislative] agent, and the form.
For with respect to the first standpoint, all those statements are applicable which we made in Chapter Seven,28 where we proved that there is no law that is not enacted for the common good. Consequently, under this division of justice, which we call legal, are included
