What is a Plaintiff in Law

A plaintiff is the party who initiates a lawsuit in a civil court, claiming to have been harmed by the actions of the defendant.

A plaintiff is the person, group, or entity that initiates a civil lawsuit by filing a complaint in court. The plaintiff claims to have suffered harm, injury, or damages caused by the actions (or inactions) of another party — the defendant — and seeks a legal remedy such as monetary compensation or injunctive relief.

Plaintiff vs. Defendant

Plaintiff — The party bringing the lawsuit; the one claiming harm
Defendant — The party being sued; the one who must respond to and defend against the claims

In criminal cases, the prosecuting party is called the prosecution or the state/government — not the plaintiff. The term "plaintiff" is specific to civil litigation.

How a Plaintiff Initiates a Lawsuit

File a complaint — The plaintiff's attorney prepares and files a formal complaint (also called a petition) with the appropriate court
Serve the defendant — The defendant must be formally notified of the lawsuit through a process called service of process
The defendant responds — The defendant files an answer or other responsive pleading
Discovery and litigation — Both parties gather evidence and prepare for trial or settlement
Resolution — The case ends through settlement, judgment, or dismissal

Burden of Proof

In civil cases, the plaintiff bears the burden of proof — they must prove their claims by a preponderance of the evidence (more likely than not, or greater than 50% certainty). This is a lower standard than the "beyond a reasonable doubt" standard in criminal cases.

Class Action Plaintiffs

In a class action lawsuit, a large group of individuals who have suffered similar harms sue collectively under a lead plaintiff (called a class representative). Class actions are common in consumer protection, securities fraud, and product liability cases.

Famous Historical Plaintiffs

Brown (Oliver Brown) — Brown v. Board of Education (1954); challenged school segregation
Roe — Roe v. Wade (1973); challenged abortion restrictions
Gideon (Clarence Gideon) — Gideon v. Wainwright (1963); established right to counsel