The Law and Society movement, as one of its major figures has put it, is “the scholarly enterprise that explains or describes legal phenomena in social terms.” Intellectual histories of the movement, which formed in the 1960s, typically begin with the Legal Realists of the 1920s and 1930s, and their argument that the content of the law was less determinate than had been assumed by legal formalists. The realists in turn reached back to Oliver Wendell Holmes and his pragmatist critique of formalism. If law was nothing more than a prediction of what the courts would do, as Holmes famously put it, and if those courts were influenced by extra-legal factors, then it became important to understand how societal factors impacted law in a systematic way. (The deeper intellectual origins of this approach go back to Henry Sumner Maine’s Ancient Law of 1861, and Montesquieu before him.)   

Though famous for his call for empiricism, Holmes was not an empirical scholar himself, and so when we look for early studies that deploy the empirical approach, we see very few. It is only with the consolidation of social science disciplines in the first decades of the 20th century that we really see systematic exploration begin. The famous Brandeis brief appears around that time, in such cases as Muller v. Oregon (1908). 

Read more at Balkinization