Rule 3.Commencing an action.

Rule 3 is one sentence, but it settles a threshold question in every case: when does a lawsuit begin? The answer is the filing of a complaint with the court, not an earlier informal step a party might take, such as sending a demand letter or seeking a temporary restraining order.

That filing date matters beyond bookkeeping. Courts have held that without a filed complaint, a court has no jurisdiction over a civil cause of action, even if the parties have already appeared before a judge on some other request. The rule also draws a boundary around what counts as an “action”: a proceeding before a court of law, not a hearing before an administrative agency acting in a quasi-judicial role.