We have seen that the entire corpus juris; the complete body of legal rules recognised and applied in English courts of justice; is divisible into two parts, which have been distinguished as the general law of the land and bodies of special law supplementing and derogating from the general law within the sphere of their special application. We have further considered in a summary manner the chief branches of this jus speciale, namely, local law, foreign law, conventional law, autonomic law, martial law, and the international law administered in prize courts. We have now to notice that the general law of England is itself divided into three parts, which are distinguished as statute law, equity, and common law. These three portions of the law are distinguished as derived from different sources, statute law is that portion of the law which is derived from legislation, including in that term, not merely the legislation of Parliament, but also the exercise of subordinate and delegated legislative power under the authority of Parliament, as, for example, regulations made under a statute. It is enacted or written law (jus scriptum) as opposed to unenacted or unwritten law (jus non scriptum) Equity, on the other hand, is that system of law which had its origin in the Court of Chancery, and which has been already considered in a previous note. It is a form of case law having its source in the judicial precedents of that court and of the modern courts by which the legal system of the Court of Chancery is now administered and developed. All the residue of the general law of England, after thus excepting statute law and equity, is known as the common law. It is a form of case law having its source in the judicial decisions of the old courts of King’s Bench, Common Pleas and Exchequer, and of the modern courts by which the system so established is now administered and developed. The case law, on the other hand, that is produced by way of the judicial interpretation of the statute law must itself be classed as forming part of the statute law from which it proceeds, for the purpose of this division of the law into statute law, equity, and common law. Common law and equity do not comprise the whole body of case law to be found in the law reports, but only that portion of case law that is derived from some other source than statutory interpretation. The case law derived from a statute is merely the statute itself, as authoritatively construed by the law courts.

The common law is the entire body of English law; the total corpus juris Angliae; with three exceptions, namely

1. statute law,
2. equity,
3. special law in its various forms.

When, therefore, it is said that a certain rule is a rule of common law, the precise significance of the statement depends on the particular branch of law which for the purpose in hand is thus contrasted with the common law. We may mean that it is a rule of common law as opposed to a rule established by statute, or as opposed to a rule of equity, or as opposed to a rule of special law; for example, a local custom, or a rule of foreign law applied in exclusion of the law of England, or a rule of military or prize law, or a conventional rule established by the parties in derogation of the common law. It is not correct, however, to regard the term common law as possessing a number of different meanings and applications. It always denotes the same thing, namely the residue of the law after excepting statute law, equity, and special law. It is not true that common law sometimes means the whole law of England except statute law, and at other times means the whole law of England except equity. If it was used in the first of these senses, it would include equity; and if it was used in the second, it would include statute law. But this is not so. The term always, in its proper sense, excludes statute law, equity, and all the forms of special law; but sometimes the particular contrast intended to be expressed is that between common law and statute law sometimes it is that between common law and equity and sometimes it is that between common law and special law.

As opposed to equity the common law is not infrequently called law simpliciter. We speak of law and equity, rather than of common law and equity, notwithstanding the fact that equity is just as truly a branch of law as the common law itself. For in its origin equity was not law at all, but was justitia naturalis administered in Chancery to correct the defects or supply the deficiencies of that strictum jus which was administered in the King’s courts of law.

In its historical origin the term common law (jus commune) was identical in meaning with the term general law as already defined. The jus commune was the general law of the land; the lex terrae; as opposed to jus speciale. By a process of historical development, however, the common law has now become, not the entire general law, but only the residue of that law after deducting equity and statute law. It is no longer possible, therefore, to use the expression common law and general law as synonymous. How this came about in the case of equity is obvious. For equity was itself until modern times a typical form of jus speciale, and therefore outside the scope of the jus commune . It was a special system of law developed and administered by a special court in conflict with the general law of the land, just as martial law or prize law is to this day. By the Judicature Act, 1873, however, equity lost its character as a body of special law, and was united with the common law as a single harmonious system of general law administered in the same courts.

The distinction between common law and equity still exists, but they are now two co-ordinate parts of a single system of general law, and no longer bear to each other that relation which made one of them general and the other special. Equity is now just as much part of the ordinary or general law of the land as is the common law itself. Nevertheless legal nomenclature has remained unchanged, and although equity has now become jus commune in truth, it has not acquired a title to that designation. Equity is a part of the general law, but not part of the common law.

The reason for the distinction between common law and statute law is not so easily intelligible. If jus commune meant originally merely the general law of the land, how is it that it does not include statute law? The explanation is apparently this, that statute law was originally conceived as a form of jus speciale derogating from the jus commune. A statute was contra jus commune, just as a local custom or the law of Chancery was. The general or common law of the land was conceived as a single, uniform, unchanging system of legal doctrine based on the immemorial customs of the realm, as authoritatively declared by the decisions of the King’s courts and applied in all cases save where some different rule, drawn from some other source, prevailed over it. Legislation, no less than local custom, was accounted one of those sources of alien rules, forming no part of the general law, but breaking in upon the established doctrine of that law by way of exceptional interference ab extra.

In modem times, however, it is no longer possible in any proper scheme of legal classification or arrangement to take this ancient view of the relation between statute and common law. The immense development of statute law in modern times and its invasion of almost every portion of the old common law has made it impossible now to treat the common law as possessing any independent existence as a special and central portion of the corpus juris, subject merely to the exceptional interference of special statutory provisions possessing the same relation to it as local custom does. Common law and statute law must now be regarded as fused into a single system of general law, just as in the case of common law and equity. Indeed, a very large portion of the general law has its sole source in statute, and the residue of the common law is undergoing a slow transformation into statute law by the process known as codification. Yet although statute law must now be recognised in any logical and practicable scheme of legal classification as being part of the general law of the land, the older mode of thought is still to be traced in the persistence of the ancient usage of legal speech. Statute law, although it is part of the general law of the land, is still distinguished in name from the common law, just as equity is still distinguished from it.

The expression common law, jus commune, was adopted by English lawyers from the canonists, who used it to denote the general law of the Church as opposed to those divergent usages (consuetudines) which prevailed in different local jurisdictions, and superseded or modified within their own territorial limits the common law of Christendom. This canonical usage must have been familiar to the ecclesiastical judges of the English law courts of the twelfth and thirteenth centuries, and was adopted by them.