Ernst Freund (30. januar 1864 – 20. oktober 1932) var en amerikansk jurist og statsviter, som var professor i statsvitenskap ved University of Chicago 1894–1902 og deretter professor i rettsvitenskap der 1903–32. Fra 1929 var han John P. Wilson-professor i jus, en såkalt "named chair". Freund jobbet hovedsakelig med utviklingen av forvaltningsrett i USA. University of Chicago Law School har etablert "Ernst Freund Distinguished Service Professorship of Law and Ethics", et professorat som nå innehas av Martha Nussbaum.
- (1897) The legal nature of corporations. University of Chicago Press.
- (1903) Empire and sovereignty. University of Chicago Press.
- (1904) Jurisprudence and legislation.
- (1904) The Police Power: Public Policy and Constitutional Rights. University of Chicago Press.
- (1908) (with Heinrich Brunner) The sources of English law. Little, Brown.
- (1911) Cases on administrative law selected from decisions of English and American courts. American casebook series.
- (1914) The problem of adequate legislative powers under state constitutions. Academy of Political Science.
- (1917) Standards of American Legislation. University of Chicago Press.
- (1919) Illegitimacy laws of the United States and certain foreign countries. Govt. Print. Off.
- (1922) (with Maurice Taylor Van Hecke) The teaching of statute law. University of North Carolina Press.
- (1923) (with Robert Virgil Fletcher, Joseph Edward Davies Cuthbert Winfred Pound, John Albert Kurtz, and Charles Nagel) The growth of American administrative law. Thomas Law Book Co.
- (1928) Administrative powers over persons and property; a comparative survey. University of Chicago Press.
- (1932) Legislative Regulation: A Study of the Ways and Means of Written Law. The Commonwealth Fund, New York.
- Kraines, Oscar. (1974) The world and ideas of Ernst Freund: the search for general principles of legislation and administrative law. University of Alabama Press.
- Firmage, Edwin Brown. (1963) Ernst Freund, pioneer: the contributions of Ernst Freund to administrative law. University of Chicago Press.