In law, a complaint is the written document a plaintiff files with a court to start a civil lawsuit. It names the parties, explains what the defendant did, identifies the legal rules that conduct violated, and tells the court what the plaintiff wants in return. Everything that follows in the case — discovery, motions, trial, judgment — grows out of what the complaint says on the day it is filed.
What a Complaint Is For
A complaint speaks to two readers at once. It gives the defendant formal notice that they are being sued and what the suit is about. It also gives the judge enough information to decide whether the dispute belongs in that court at all.
The document does more than open the file. It also sets the outer edges of the case. A plaintiff cannot pursue a theory of liability or a type of damages that the complaint did not raise, at least not without first amending it. For that reason the complaint functions as the blueprint for the rest of the lawsuit, not just its first page.
What Has to Be in a Complaint
Federal courts require three things in every complaint: a short, plain statement of the court’s jurisdiction, a short, plain statement of the claim showing the plaintiff is entitled to relief, and a demand for the relief sought.1Legal Information Institute. Federal Rules of Civil Procedure Rule 8 – General Rules of Pleading State courts use similar structures. In practice, a complaint breaks into several distinct sections.
Caption and Parties
The caption sits at the top of the first page and identifies the court, the names of all parties, and the case number assigned by the clerk.2Office of the Law Revision Counsel. Federal Rules of Civil Procedure Rule 10 – Form of Pleadings A party section below the caption usually adds addresses and, for businesses, the type of entity, so the court can confirm it has authority over everyone named.
Jurisdiction and Venue
This section explains why the chosen court has power over the dispute and why it is the right geographic location. Jurisdiction concerns the court’s authority over the type of case and the parties. Venue is proper where the defendant lives or where a substantial part of the events giving rise to the claim occurred.3Office of the Law Revision Counsel. 28 USC 1391 – Venue Generally Getting either wrong can lead to dismissal or transfer.
Factual Allegations
The body of the complaint tells what happened, from the plaintiff’s perspective, in numbered paragraphs.2Office of the Law Revision Counsel. Federal Rules of Civil Procedure Rule 10 – Form of Pleadings Each paragraph covers one set of facts, usually in chronological order. The numbering matters because the defendant’s eventual response will reply paragraph by paragraph.
Courts require those facts to be more than possible. They must be plausible. A complaint built on bare legal conclusions, with no factual detail behind them, risks dismissal. The plausibility standard, developed in federal case law interpreting Rule 8, asks whether the facts stated give the court enough to reasonably infer the defendant is liable.
Causes of Action
After the facts, the complaint lists the specific legal claims, called causes of action. Each is a separate legal theory, such as negligence, breach of contract, or fraud. This section ties the facts to the law, explaining how the defendant’s conduct violated a duty owed to the plaintiff. One lawsuit can include several causes of action based on the same events.
Prayer for Relief
The prayer for relief is where the plaintiff tells the court what they want. That can be money for losses like medical bills or lost income. It can also be non-monetary, such as a court order requiring the defendant to stop doing something. A complaint can request several kinds of relief at once.1Legal Information Institute. Federal Rules of Civil Procedure Rule 8 – General Rules of Pleading
Signature and Certification
Every complaint must be signed, either by an attorney or by a plaintiff who is representing themselves.4Legal Information Institute. Federal Rules of Civil Procedure Rule 11 – Signing Pleadings, Motions, and Other Papers The signature is a certification. It states that the claims rest on a reasonable investigation, that the legal arguments have merit, and that the lawsuit is not being filed to harass or waste the court’s time. A frivolous complaint can draw sanctions, including an order to pay the other side’s legal fees.
When Stricter Pleading Rules Apply
Most complaints need only meet the general plausibility standard. Some claims require more. Allegations of fraud or mistake must be stated with particularity, meaning the complaint has to spell out who said what, when, where, and how the statement was misleading.5Legal Information Institute. Federal Rules of Civil Procedure Rule 9 – Pleading Special Matters Vague fraud allegations are one of the most common reasons courts dismiss complaints in business litigation.
Special damages, meaning losses that are not an obvious result of the harm such as lost future business opportunities, also have to be specifically identified in the complaint.5Legal Information Institute. Federal Rules of Civil Procedure Rule 9 – Pleading Special Matters
Filing Deadlines and Court Fees
Every civil claim has a filing deadline called a statute of limitations. Miss it and the court will almost certainly dismiss the case, no matter how strong the evidence. These deadlines vary by claim and by jurisdiction. Federal civil actions arising under acts of Congress generally must be filed within four years unless a specific statute sets a different period.6Office of the Law Revision Counsel. 28 USC 1658 – Time Limitations on the Commencement of Civil Actions Arising Under Acts of Congress State-law claims have their own periods, ranging from one year for defamation to six or more years for breach of contract depending on the state.
The clock usually starts when the harm occurs, but not always. Under the discovery rule, the deadline can start when the plaintiff knew or should have known about the injury, which matters in cases involving hidden fraud or slow-developing medical conditions. Courts can also pause the clock in limited circumstances, such as when a defendant actively concealed the wrongdoing.
The lawsuit officially begins when the complaint is filed with the court clerk. In federal district court the statutory filing fee is $350 plus a $55 administrative fee, for a total of $405.7Office of the Law Revision Counsel. 28 USC 1914 – District Court Filing and Miscellaneous Fees8U.S. District Court. Court Fees State court fees vary widely, from under $100 to over $400. A plaintiff who cannot afford the fee can ask the court for permission to proceed without paying by submitting an affidavit about their finances, and the court decides whether to waive it.9Office of the Law Revision Counsel. 28 USC 1915 – Proceedings in Forma Pauperis Most state courts have similar fee-waiver programs.
Delivering the Complaint to the Defendant
Filing the complaint is only half the job. The defendant must also be formally served with a copy of the complaint and a summons, which is the official court document telling the defendant they are being sued and must respond by a set date.10Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons
In federal court, anyone at least 18 years old and not a party to the case can serve the documents. That covers professional process servers, sheriff’s deputies, or a friend, though most plaintiffs hire a professional. The court can also order a U.S. marshal to serve the papers, and must do so when the plaintiff has a fee waiver. A plaintiff can also mail a defendant a request to waive formal service; a defendant who agrees gets 60 days to respond instead of the usual 21, and one who refuses without good cause can be ordered to pay the cost of formal service.10Legal Information Institute. Federal Rules of Civil Procedure Rule 4 – Summons
After service, the person who delivered the documents files a proof of service with the court, usually a sworn statement showing when, where, and how it happened. Without it, the court has no record the defendant was properly notified.
What Happens After the Complaint Is Filed
Once served, the defendant has a limited window to respond. In federal court the deadline is 21 days after service, or 60 days if service was waived.11Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections State court deadlines vary but commonly fall between 20 and 30 days.
The Answer
The most common response is an answer. The defendant goes through each numbered paragraph of the complaint and admits it, denies it, or states they lack enough information to respond, which the court treats as a denial. The answer is also where the defendant raises affirmative defenses, meaning legal reasons the plaintiff should lose even if the facts are true. Common ones include an expired statute of limitations, the plaintiff’s own negligence contributing to the harm, and waiver.1Legal Information Institute. Federal Rules of Civil Procedure Rule 8 – General Rules of Pleading A defendant with their own claim arising from the same events must bring it in the answer as a counterclaim or lose the right to raise it later.12Legal Information Institute. Federal Rules of Civil Procedure Rule 13 – Counterclaim and Crossclaim
Motion to Dismiss
Instead of answering, a defendant can ask the court to throw out the case by filing a motion to dismiss. The most common grounds are failure to state a claim (the facts, even if true, do not add up to a viable legal claim), lack of jurisdiction, improper venue, and insufficient service. Federal Rule 12(b) lists seven grounds in total.11Legal Information Institute. Federal Rules of Civil Procedure Rule 12 – Defenses and Objections When a complaint has real legal defects, a motion to dismiss can end a case in weeks rather than years.
Default Judgment
If a defendant ignores the complaint and files nothing, the plaintiff can ask the court for a default judgment. The clerk first enters a default, confirming the failure to respond. For claims involving a specific dollar amount, the clerk can enter judgment directly. For everything else, the court holds a hearing to determine what is owed.13Legal Information Institute. Federal Rules of Civil Procedure Rule 55 – Default and Default Judgment Courts still review whether the complaint states a valid claim, but a defaulting defendant has no say in the outcome. Setting aside a default judgment later is possible but difficult.
Amending the Complaint
Complaints rarely stay the same through an entire case. A plaintiff can amend once without the court’s permission, as long as they do so within 21 days of serving the complaint, or within 21 days after the defendant files an answer or motion to dismiss, whichever comes first. After that, the plaintiff needs the defendant’s written consent or the court’s permission. Courts are told to grant permission freely when justice so requires, which in practice means amendments are usually allowed unless the defendant would be unfairly prejudiced, the plaintiff has already had several chances, or the proposed amendment would still fail to state a valid claim.14Legal Information Institute. Federal Rules of Civil Procedure Rule 15 – Amended and Supplemental Pleadings Plaintiffs who receive a motion to dismiss often amend to fix the identified defects rather than fight the motion head-on.