Plaintiff vs. Claimant vs. Complainant: What’s the Difference?

If someone starts a legal proceeding, should you call that person a plaintiff, claimant, or complainant?

The answer depends on the type of proceeding and the legal system involved.

In U.S. civil litigation, the person who starts a lawsuit is usually called the plaintiff. In England and Wales, the equivalent party in most civil proceedings is generally called the claimant. A complainant, by contrast, is usually someone who makes or files a complaint, which may occur in an administrative, regulatory, disciplinary, employment, or other type of proceeding.

For international lawyers and law students, understanding these distinctions is important because using the wrong term can make otherwise good Legal English sound inaccurate or unfamiliar.

Plaintiff, Claimant, and Complainant: Quick Comparison

These categories are useful, but they are not universal rules. Legal terminology varies between jurisdictions and according to the type of proceeding.

What Is a Plaintiff?

A plaintiff is the party who begins a civil lawsuit against another party.

In U.S. civil litigation, the plaintiff normally starts the action by filing a complaint against the defendant. The plaintiff then asks the court for some form of legal remedy, such as damages or an injunction.

For example:

The plaintiff filed a breach of contract action against the defendant.

The plaintiff is seeking $100,000 in damages.

Counsel for the plaintiff called the first witness.

The Legal Information Institute at Cornell defines a plaintiff as the party who initiates a civil lawsuit by filing a complaint. 

Plaintiff and Defendant

These two terms usually appear together:

Plaintiff → the party bringing the civil action
Defendant → the party against whom the action is brought

For example:

ABC Corporation sued XYZ Limited for breach of contract. ABC Corporation is the plaintiff, and XYZ Limited is the defendant.

In criminal proceedings, however, we normally do not describe the government as the plaintiff in ordinary U.S. Legal English. Criminal cases involve the prosecution and the defendant.

What Is a Claimant?

A claimant is a person or organization that makes a claim.

This term is particularly important for international lawyers because it is used in several different legal contexts.

Claimant in England and Wales

In the civil courts of England and Wales, the person bringing the claim is generally called the claimant rather than the plaintiff.

The Civil Procedure Rules define a claimant simply as a person who makes a claim, and HM Courts & Tribunals Service describes the claimant as the person bringing the claim to court.

For example:

The claimant alleges that the defendant breached the contract.

A U.S. lawyer might describe essentially the same procedural roles as:

The plaintiff alleges that the defendant breached the contract.

This does not mean that plaintiff and claimant are universally interchangeable. The appropriate term depends on the procedural system you are working in.

Other Uses of Claimant

Claimant is also common outside ordinary court litigation.

For example, you may hear about:

• an insurance claimant
• a benefits claimant
• a claimant in arbitration
• someone claiming compensation or another legal entitlement

For example:

The claimant submitted evidence of the damage to the insurance company.

The basic idea is consistent: the claimant is asserting a claim to some right, remedy, payment, or other legal entitlement.

What Is a Complainant?

A complainant is generally a person who makes or files a complaint.

This word is especially common in proceedings that do not follow the standard plaintiff-versus-defendant structure of an ordinary civil lawsuit.

Depending on the legal system and type of proceeding, a complainant may file a complaint with:

• a government agency;
• a regulatory body;
• an employer;
• a professional disciplinary authority;
• an equality or discrimination body;
• another administrative organization.

For example:

The complainant alleged that the employer had discriminated against her.

The agency notified the respondent of the complainant’s allegations.

Various U.S. regulations define a complainant as the person or entity filing a complaint, although the exact procedural meaning depends on the particular proceeding. 

Complainant Does Not Necessarily Mean Plaintiff

This distinction is important.

A person can be a complainant without being the plaintiff in a civil lawsuit.

For example, an employee might file a discrimination complaint with an administrative agency. At that stage, the employee may be called the complainant.

If the dispute later becomes a civil lawsuit, that same person might then be called the plaintiff or claimant, depending on the jurisdiction and procedure.

The terminology describes the person's procedural role, not simply the fact that the person believes something wrong happened.

Plaintiff vs. Claimant: Are They the Same?

Sometimes they perform essentially the same role, but the terminology differs by legal system.

A useful general distinction is:

U.S. civil litigation → plaintiff

Civil litigation in England and Wales → claimant

The terminology changed in England and Wales with the modern Civil Procedure Rules, which use claimant and defendant in civil proceedings. Current court rules consistently identify the party bringing the claim as the claimant.

For international lawyers, this means you should avoid automatically replacing one term with the other.

Consider the source of the document.

If you are reading a U.S. federal court opinion, plaintiff will normally sound natural.

If you are working with civil proceedings in England and Wales, claimant will generally be the expected term.

Claimant vs. Complainant

These two words are easier to confuse because they are both formed from nouns:

• claim → claimant
• complaint → complainant

But they describe different actions.

• A claimant makes a claim.
• A complainant makes a complaint.

For example:

The claimant seeks compensation for breach of contract.

The person is asserting a legal claim for a remedy.

Compare:

The complainant reported the alleged misconduct to the disciplinary authority.

The person has initiated a complaint process.

The distinction becomes clearer if you focus on the underlying noun rather than trying to memorize the titles separately.

What About “Complaint”?

There is an additional complication for Legal English learners: complaint itself has more than one legal use.

In U.S. civil procedure, a complaint is the pleading that normally begins a civil lawsuit. The plaintiff files the complaint against the defendant.

So we can say:

The plaintiff filed a complaint.

That does not normally mean that the plaintiff should therefore be called the complainant in the lawsuit.

This is a good example of why Legal English cannot always be learned simply by looking at word families.

The accepted procedural terminology matters.

Plaintiff, Claimant, or Complainant? Practical Examples

Consider these situations.

U.S. breach of contract lawsuit

Maria files a federal civil lawsuit against a company for breach of contract.

• Maria = plaintiff
• Company = defendant

Civil claim in England and Wales

Maria brings a breach of contract claim in an English court.

• Maria = claimant
• Company = defendant

Regulatory complaint

Maria files a complaint with a regulatory authority alleging professional misconduct.

• Maria = complainant

The other party might be called the respondent, depending on the relevant procedure.

Insurance claim

Maria asks her insurer to compensate her for damage covered by her insurance policy.

• Maria = claimant

There may be no plaintiff, defendant, or complainant at all unless the dispute later develops into some form of legal proceeding.

Which Term Should International Lawyers Use?

The safest approach is to follow the terminology used by the relevant jurisdiction and procedure.

Do not assume that one English legal term works everywhere.

When reading or drafting legal documents:

• use plaintiff when that is the established term for the party bringing the civil action;
• use claimant when the procedure describes the person as bringing a claim;
• use complainant when the person is making or filing a complaint;
• check the applicable court rules or procedural regulations when you are unsure.

This is especially important for lawyers working across common-law systems. Two terms may refer to very similar roles but still sound incorrect if they are used in the wrong procedural setting.

Understanding differences like these is an important part of developing strong Legal English skills.

Conclusion

Plaintiff, claimant, and complainant can all describe someone who initiates some form of legal process, but they are not synonyms.

A plaintiff typically brings a civil lawsuit, especially in U.S. Legal English. A claimant makes a claim and is the standard term for the party bringing most civil proceedings in England and Wales. A complainant makes or files a complaint, often in an administrative, regulatory, disciplinary, or similar procedure.

For international lawyers, the key is to identify the person's procedural role and jurisdiction rather than trying to apply one term to every legal dispute.

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