has typically cast it as divided between a conservative and liberal faction, with two critical swing votes. The conservative Justices Pierce Butler, James Clark McReynolds, George Sutherland and Willis Van Devanter were known as "The Four Horsemen". Opposed to them were the liberal Justices Louis Brandeis, Benjamin Cardozo and Harlan Fiske Stone, dubbed "The Three Musketeers". Chief Justice Charles Evans Hughes and Justice Owen Roberts were regarded as the swing votes on the court. Some recent scholarship has eschewed these labels since they suggest more legislative, as opposed to judicial, differences. While it is true that many rulings of the 1930s Supreme Court were deeply divided, with four justices on each side and Justice Roberts as the typical swing vote, the ideological divide this represented was linked to a larger debate in U.S. jurisprudence regarding the role of the judiciary, the meaning of the Constitution, and the respective rights and prerogatives of the different branches of government in shaping the judicial outlook of the Court. At the same time, however, the perception of a conservative/liberal divide does reflect the ideological leanings of the justices themselves. As William Leuchtenburg has observed: Whatever the political differences among the justices, the clash over the constitutionality of the New Deal initiatives was tied to clearly divergent legal philosophies which were gradually coming into competition with each other: legal formalism and legal realism. During the period c. 1900 – c. 1920, the formalist and realist camps clashed over the nature and legitimacy of judicial authority in common law, given the lack of a central, governing authority in those legal fields other than the precedent established by case law—i.e. the aggregate of earlier judicial decisions. This debate spilled over into the realm of constitutional law. Realist legal scholars and judges argued that the constitution should be interpreted flexibly and judges should not use the Constitution to impede legislative experimentation. One of the most famous proponents of this concept, known as the Living Constitution, was U.S. Supreme Court justice Oliver Wendell Holmes, Jr., who said in Missouri v. Holland the "case before us must be considered in the light of our whole experience and not merely in that of what was said a hundred years ago". The conflict between formalists and realists implicated a changing but still-persistent view of constitutional jurisprudence which viewed the U.S. Constitution as a static, universal, and general document not designed to change