Supreme Court Justice Oliver Wendell Holmes, Jr. was the precursor and hero of the Legal Realism movement. Born in 1841 in Massachusetts, Holmes was a Civil War veteran who was wounded three times in battle, including the battle of Antietam, each time recovering and returning to the front. After the war, he studied at Harvard and there met William James, a year younger, who was studying medicine. He took his LL. B. in 1866. In 1870 he was made editor of the American Law Review. In 1873, his edition of Kent's Commentaries appeared. These early papers state the fundamentals of what became his lectures on "The Common Law." This sets the tone for the Legal Realism movement :
The life of the law has not been logic; it has been experience. The felt necessities of the time, the prevalent moral and political theories, intuitions of public policy avowed or unconscious, even with the prejudices which judges share with their fellow-men, have had a great deal more to do than the syllogism in determining the rules by which men should be governed. The law embodies the story of a nation's development through many centuries, and it cannot be dealt with as if it contained only the axioms and corollaries of a book of mathematics.

He taught law at Harvard, and then sat on the Massachusetts Supreme Court for twenty years. He was Massachesetts' Chief Justice when, in 1901, Theodore Roosevelt noted that Holmes's "labor decisions" were criticized by "some of the big railroad men and other members of large corporations." TR found this "a strong point in Judge Holmes's favor" when he appointed him to the Supreme Court.

Soon thereafter, the Court decided Lochner v. New York, 198 US 45, 76 (1905). Lochner came to be regarded during the New Deal, and ever since, as the epitome of empty formalism in the law. The case involved an early attempt at a fair wage and hour law. The Legislature of the State of New York determined that bakers should not have to work more than sixty (60) hours a week. The baking industry challenged the law, and the Supreme Court held that it deprived the bakers of “liberty” without due process in violation of the Fourteenth Amendment, that is, the freedom to enter into an work contract. It should be noted that at this time, workers lacked the legal right to unionize and bargain collectively for fair terms in such a contract. Justice Holmes wrote a dissenting opinion. Id. 198 U.S. 45, 75.

I regret sincerely that I am unable to agree with the judgment in this case, and that I think it my duty to express my dissent.
This case is decided upon an economic theory which a large part of the country does not entertain. If it were a question whether I agreed with that theory, I should desire to study it further and long before making up my mind. But I do not conceive that to be my duty, because I strongly believe that my agreement or disagreement has nothing to do with the right of a majority to embody their opinions in law. It is settled by various decisions of this court that state constitutions and state laws may regulate life in many ways which we as legislators might think as injudicious, or if you like as tyrannical, as this, and which, equally with this, interfere with the liberty to contract. Sunday laws and usury laws are ancient examples. A more modern one is the prohibition of lotteries. The liberty of the citizen to do as he likes so long as he does not interfere with the liberty of others to do the same, which has been a shibboleth for some well-known writers, is interfered with by school laws, by the Postoffice, by every state or municipal institution which takes his money for purposes thought desirable, whether he likes it or not. The 14th Amendment does not enact Mr. Herbert Spencer's Social Statics. * * * Some of these laws embody convictions or prejudices which judges are likely to share. Some may not. But a Constitution is not intended to embody a particular economic theory, whether of paternalism and the organic relation of the citizen to the state or of laissez faire. It is made for people of fundamentally differing views, and the accident of our finding certain opinions natural and familiar, or novel, and even shocking, ought not to conclude our judgment upon the question whether statutes embodying them conflict with the Constitution of the United States.
General propositions do not decide concrete cases. The decision will depend on a judgment or intuition more subtle than any articulate major premise. But I think that the proposition just stated, if it is accepted, will carry us far toward the end. Every opinion tends to become a law. I think that the word 'liberty,' in the 14th Amendment, is perverted when it is held to prevent the natural outcome of a dominant opinion, unless it can be said that a rational and fair man necessarily would admit that the statute proposed would infringe fundamental principles as they have been understood by the traditions of our people and our law. It does not need research to show that no such sweeping condemnation can be passed upon the statute before us. A reasonable man might think it a proper measure on the score of health. Men whom I certainly could not pronounce unreasonable would uphold it as a first instalment of a general regulation of the hours of work. Whether in the latter aspect it would be open to the charge of inequality I think it unnecessary to discuss.