Papers filed in court by an injured party to begin a lawsuit by setting out facts and legal claims (usually called causes of action). The person filing the complaint is called the plaintiff and the other party is called the defendant. In some states and in some types of legal actions, such as divorce, complaints are called petitions and the person filing is called the petitioner. The plaintiff's complaint must be served on the defendant, who then has the opportunity to respond by filing an answer. A complaint filing must be accompanied by a filing fee payable to the court clerk, unless the party asks a judge to waive the fee based on inability to pay.