Legal process (or sometimes "process"), are the proceedings in any civil lawsuit or criminal prosecution and, particularly, describes the formal notice or writ used by a court to exercise jurisdiction over a person or property. Such process is usually "served" upon a party, to compel that party to come to court, and may take the form of a summons, mandate, subpoena, warrant, or other written demand issued by a court.

The legal process school (sometimes "legal process theory") was a movement within American law that attempted to chart a third way between legal formalism and legal realism. Drawing its name from Hart & Sacks' textbook The Legal Process (along with Hart & Wechsler's textbook The Federal Courts and the Federal System considered a primary canonical text of the school), it is associated with scholars such as Herbert Wechsler, Henry Hart, Albert Sacks and Lon Fuller, and their students such as John Hart Ely and Alexander Bickel. The school grew in the 1950s and 1960s. To this day, the school's influence remains broad.