§ 122 Agreements
Of all vestitive facts, acts in the law are the most important; and among acts in the law, agreements are entitled to the chief place. Unilateral acts are comparatively infrequent and unimportant. The residue of this chapter will therefore be devoted to the consideration of the grounds, modes, and conditions of the operation of agreement as an instrument of the creation, transfer, and extinction of rights. A considerable portion of what is to be said in this connection will, however, be applicable mutatis mutandis to unilateral acts also.
The importance of agreement as a vestitive fact lies in the universality of its operation. There are few rights which cannot be acquired through the assent of the persons upon whom the correlative duties are to be imposed. There are few rights which cannot be transferred to another by the will of him in whom they are presently vested. There are few which are not extinguished when their owner no longer desires to retain them. Of that great multitude of rights and duties of which the adult member of a civilised community stands possessed, the great majority have their origin in agreements made by him with other men. By agreements of contrary intent he may strip himself almost as destitute of rights and duties, as when in the scantiest of juridical vesture he made his first appearance before the law. Invito beneficium non datur,310 said the Romans.
By what reasons, then, is the law induced to allow this far-reaching operation to the fact of agreement? Why should the mere consent of the parties be permitted in this manner to stand for a title of right? Are not rights the subject-matter of justice, and is justice a mere matter of convention varying with the wills of men?
The reasons are two in number. Agreement is in the first place evidential of right, and in the second place constitutive of it. There is in general no better evidence of the justice of an arrangement than the fact that all persons whose interests are affected by it have freely and with full knowledge consented to it. Men are commonly good judges of their own interests, and in the words of Hobbes “there is not ordinarily a greater sign of the equal distribution of anything, than that every man is contented with his share.” When, therefore, all interests are satisfied, and every man is content, the law may safely presume that justice has been done, and that each has received his own. The determination of the law is needed only in default of the agreement of the parties. Hence it is, that he who agrees with another in any declaration of their respective rights and duties will not be suffered to go back from his word, and will not be heard to dispute the truth of his declaration. The exceptions to this rule are themselves defined by equally rigid rules; and he who would disclaim a duty which he has thus imposed upon himself, or reclaim a right which he has thus transferred or abandoned, must bring himself within one of those predetermined exceptions. Otherwise he will be held bound by his own words.
This conclusive presumption of the truth of consensual declarations of right is, however, only one of the foundations of the law of agreement. Consent is in many cases truly constitutive of right, instead of merely evidential of it. It is one of the leading principles of justice to guarantee to men the fulfilment of their reasonable expectations. In all matters that are otherwise indifferent, expectation is of predominant influence in the determination of the rule of right, and of all the grounds of rational expectation there is none of such general importance as mutual consent. “The human will,” says Aquinas, “is able by way of consent to make a thing just; provided that the thing is not in itself repugnant to natural justice.”311
There is an obvious analogy between agreement and legislation—the former being the private and the latter the public declaration and establishment of rights and duties. By way of legislation the state does for its subjects that which in other cases it allows them to do for themselves by way of agreement. As to the respective spheres of these two operations, the leading maxim is Modus et conventio vincunt legem. Save when the interests of the public at large demand a different rule, the autonomy of consenting parties prevails over the legislative will of the state. So far as may be, the state leaves the rule of right to be declared and constituted by the agreement of those concerned with it. So far as possible, it contents itself with executing the rules which its subjects have made for themselves. And in so doing it acts wisely. For in the first place, the administration of justice is enabled in this manner to escape in a degree not otherwise attainable the disadvantages inherent in the recognition of rigid principles of law. Such principles we must have; but if they are established pro re nata by the parties themselves, they will possess a measure of adaptability to individual cases which is unattainable by the more general legislation of the state itself. Amid the infinite diversities and complexities of human affairs the state wisely despairs of truly formulating the rules of justice. So far as possible, it leaves the task to those who by their nearness to the facts are better qualified for it. It says to its subjects: Agree among yourselves as to what is just in your individual concerns, and I shall enforce your agreement as the rule of right.
In the second place, men are commonly better content to bear the burdens which they themselves have taken up, than those placed upon them by the will of a superior. They acquiesce easily in duties of their own imposition, and are well pleased with rights of their own creation. The law or the justice which best commends itself to them is that which they themselves have made or declared. Wherefore, instead of binding its subjects, the state does well in allowing them to bind themselves.