THE investigation of the practice of the review of legislative acts by the courts to test their conformity with the provisions of written constitutions has involved the consideration of theories of natural law and of ideas of superior fundamental laws. These theories and ideas are closely related to doctrines of higher or superior laws which have accompanied the growth of legal systems. Due to the importance of such ideas in public law and in the development of limits on the different branches of modern governments, a study has been made of the main stages in the evolution of higher law concepts. A considerable part of the study is devoted to the significance of natural law ideas in the interpretation of the state and federal constitutions in the United States, where natural law doctrines have been extensively applied. The review of the growth of natural law ideas and the presentation of representative opinions of European publicists are intended to aid in the interpretation of American theories and as a perspective to evaluate some modern tendencies in constitutional development in the United States.

It is evident that the concepts of natural law and of fundamental law are frequently associated. Though natural law may be thought of with little relation to the notion involved in fundamental laws, and fundamental laws may be conceived unrelated to natural law, it is customary at various stages of such analyses for one idea to merge into the other. Carlyle, in speaking of the views of the Roman jurists on natural law, doubted whether any of the lawyers had very clear conceptions upon the matter. As a matter of fact all theories of natural law have a singular vagueness which is both an advantage and disadvantage in the application of the theories.

Philosophers emphasize the fact that such a term as natural law is a value concept and the result of an attitude — an attitude which presupposes certain psychic processes. Such value concepts are in one sense subjective, and in another sense they have a normative objectivity. It is beyond the scope of this treatise to deal with the philosophical and psychological processes which underlie natural law thinking. The purpose is to present different types of theories in their legal development and to note their applications by jurists and lawyers.

Articles by the writer relating in part to this subject have appeared in the Yale Law Journal, Illinois Law Review, and the Texas Law Review. The portions used from these articles have been rewritten in a continuous account with the exception of extracts from the Texas Law Review which are reprinted with some minor changes by permission of the editors. In the presentation of ideas relating to natural law in European countries, I have received invaluable assistance from Professor Georgio del Vecchio, Rector of the University of Rome, and Professor Louis Le Fur of the Faculty of Law of the University of Paris, who have favored me with very useful Italian and French publications relating to natural law. In addition I have been accorded the privilege by authors and publishers to translate and reprint portions of the works of European authorities on natural law. I take pleasure in expressing my appreciation for aid received from Dean Roscoe Pound, who has frequently indicated in books and in articles the influence of natural law concepts in the development of American law.


November, 1929