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FindLaw Legal Dictionary

The FindLaw Legal Dictionary -- free access to over 8260 definitions of legal terms. Search for a definition or browse our legal glossaries.


Complaint, n

What Is a Complaint?

A legal complaint, also called a petition, is typically the first document filed in a lawsuit. It is the pleading that starts a lawsuit.

A complaint:

  • Identifies the parties, including their names and addresses
  • Explains why the court has jurisdiction to hear the case
  • States the plaintiff's claims against the defendant
  • Goes over what happened, according to the plaintiff (states the facts)
  • Sets forth the plaintiff's request for relief

Types of Complaints

There may be other complaints filed in a lawsuit, including:

  • Amended complaint/supplemental complaint: A complaint that changes or adds to the original complaint to correct information or add relevant information. A plaintiff must have court approval to submit a supplemental or amended complaint.
  • Third-party complaint: A third-party complaint is a document typically filed by the defendant to a lawsuit. It states that another party (a "third party") caused some or all of the plaintiff's harm and is partially or fully responsible for the damages.

Criminal Complaints

A criminal complaint lists the alleged offenses (charges) against a defendant and the facts surrounding those offenses.

Typically, the government (through a prosecutor) files a criminal complaint with the court. A court will determine whether the complaint shows probable cause. This initiates the criminal case and often precedes an arrest warrant.

Legal Complaint Example

Many state court resources offer example complaints, or templates to help you begin your complaint. You can also find a sample complaint letter for a civil case on

Relevant Rules and Court Cases

Federal Rules of Civil Procedure, Title III: Federal civil court rules explaining what a complaint is and what it must include.

State Rules of Practice: Many states have their own rules for complaints. See, for example, the specific requirements for a complaint in New York: CVP Rule 2101.

Bell Atlantic Corp. v. Twombly, 550 US 544 (2007): The U.S. Supreme Court held that a complaint requires enough factual information to show that a relief was "plausible on its face," rather than simply conceivable.

Ashcroft v. Iqbal, 566 US 662 (2009): Further explaining the need for factual allegations to meet the standard of Federal Rules of Civil Procedure, Rule 8.

Additional Resources:

Key Takeaways: 

  • A legal complaint is typically the first document in a lawsuit
  • Filing a complaint starts the lawsuit
  • Other complaints can be filed in a lawsuit, including amended complaints and third-party complaints
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