What is "form of action"

The forms of action were the different procedures by which a legal claim could be made for much of history of the English common law. Depending on the court, a plaintiff would purchase a writ in Chancery (or file a bill) which would set in motion a series of events eventually leading to a trial in one of the medieval common law courts. Each writ entailed a different set of procedures and remedies which together amounted to the "form of action".

The forms of action were abolished during the 19th century, but they have left an indelible mark on the law. In the early Middle Ages, the focus was on the procedure that was employed to bring one's claim to the royal courts of King's Bench or Common Pleas: it was the form of one's action, not its substance, which occupied legal discussion. This restrictive approach is one of the reasons which attracted litigants to petition the King directly, which eventually led to the development of a separate court known as the Court of Chancery, from which the body of law known as Equity derives. Modern English law, as in most other legal systems, now looks to substance rather than to form: a claimant need only demonstrate that he or she has a valid cause of action.