Austrian legal scholar and teacher generally credited with founding the discipline of the sociology of law.

Educated in law at the University of Vienna, Ehrlich taught there for several years and then served as associate professor of Roman law at the University of Czernowitz (1899–1914). As a young man he converted from Judaism to Roman Catholicism, but late in life he devoted much of his attention to the problems of the Jews. anti-Semitism prevented him from teaching after World War I.

Ehrlich's sociology of law was based in part on the free-law, or sense-of-justice, doctrine formulated in Germany by Hermann Kantorowicz (Kantorowicz, Hermann). He recognized two complementary sources of law: first, legal history and jurisprudence—i.e., precedents that seem useful, along with their written explications—and second, “living law” as manifested in current social custom. Because the second component was more novel, readers of Ehrlich tended to overlook the first, and some believed mistakenly that he had dismissed formal law entirely. His major work was Fundamental Principles of the Sociology of Law (1913), which discusses the laws of different countries and concludes that legal development takes place less through legislation or judicial science than through the development of society itself.