§ 48 Sources of Law and Sources of Rights
The sources of law may also serve as sources of rights. By a source or title of rights is meant some fact which is legally constitutive of rights. It is the de facto antecedent of a legal right just as a source of law is the de facto antecedent of a legal principle. An examination of any legal system will show that to a large extent the same classes of facts which operate as sources of law operate as sources of rights also. The two kinds of sources form intersecting circles. Some facts create law but not rights; some create rights but not law; some create both at once. An act of Parliament for example is a typical source of law; but there are numerous private acts which are clearly titles of legal rights. Such is an act of divorce, or an act granting a pension for public services, or an act incorporating a company. So in the case of precedent, the judicial decision is a source of rights as between the parties to it, though a source of law as regards the world at large. Regarded as creative of rights, it is called a judgment; regarded as creative of law, it is called a precedent. So also immemorial custom does upon occasion give rise to rights as well as to law. In respect of the former operation, it is specifically distinguished as prescription, while as a source of law it retains the generic title of custom. That an agreement operates as a source of rights is a fact too familiar to require illustration. The proposition which really needs emphatic statement in this case is that agreement is not exclusively a title of rights, but is also operative as a source of law.