What document initiates a civil lawsuit?

The document that initiates a civil lawsuit is the complaint. This is the formal legal document that a plaintiff files with the court to begin the legal process. The complaint outlines the plaintiff's claims against the defendant, including the basis for the court's jurisdiction, the facts of the case, and the relief being sought. It serves not only to inform the defendant of the allegations they are facing but also establishes the legal framework for the entire lawsuit.

In contrast, a summons is a document that notifies the defendant that a lawsuit has been filed against them and provides instructions on how to respond. An affidavit is a sworn statement used in court, but it does not initiate a lawsuit. A response, often referred to as an answer, is the defendant’s formal reply to the complaint, addressing the claims made by the plaintiff. Thus, the complaint is clearly marked as the initiating document of a civil lawsuit, making it the correct answer.