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Foundations · Tier 1

Plaintiff, defendant, petitioner, respondent: and a few others

beginner5 min read

Plaintiff, defendant, petitioner, respondent: and a few others

If you've spent any time around courts, you've heard parties called by different names: plaintiff, defendant, petitioner, respondent, appellant, appellee, prosecution, accused. Different cases use different vocabulary, but the underlying roles are usually one of two: the side bringing the case, and the side defending against it.

This lesson explains who's called what, in which contexts, and why.

The two basic roles

Most cases boil down to two parties:

  1. The side bringing the case. They started it. They're asking the court to do something. They have the burden of proof.
  2. The side defending the case. They didn't choose to be in court. They have to respond. They're trying to keep the other side from winning.

The names change depending on the type of case. The roles don't.

Civil lawsuits: plaintiff and defendant

In a typical civil lawsuit, the side bringing the case is the plaintiff. The side being sued is the defendant.

  • The plaintiff filed the complaint.
  • The plaintiff has the burden of proof.
  • The plaintiff is asking for something: usually money damages, sometimes an injunction.
  • The defendant has to respond to the complaint.
  • The defendant raises defenses.
  • The defendant might also have counterclaims against the plaintiff (in which case, for the counterclaim, the defendant is functionally a plaintiff).

This terminology covers the vast majority of civil cases: contract disputes, personal injury, employment, consumer issues, business litigation.

Cases are usually styled with the plaintiff first: Smith v. Jones. The plaintiff is Smith; the defendant is Jones.

Criminal cases: prosecution (or government) and defendant

In criminal cases, the side bringing the case is the government: represented by a prosecutor. The side being charged is still called the defendant.

Criminal case names typically put the government first:

  • United States v. Williams: federal criminal case
  • People v. Garcia: California criminal case (and some other states)
  • State v. Lee: most state criminal cases
  • Commonwealth v. Davis: Pennsylvania, Massachusetts, Virginia, and Kentucky criminal cases

The "defendant" in a criminal case is the same word, but the context (and the rights involved) is very different from a civil defendant.

Family law, probate, and special proceedings: petitioner and respondent

Some kinds of cases use petitioner and respondent instead of plaintiff and defendant. The role is the same: petitioner is the one who started the case; respondent is the other side.

This terminology is most common in:

  • Divorce: the spouse who filed is the petitioner; the other spouse is the respondent
  • Child custody and support: same pattern
  • Restraining orders: petitioner asks for the order; respondent is the alleged abuser
  • Probate: petitioner is the one asking the court to admit a will or appoint a personal representative
  • Adoption: petitioner is the prospective adopter
  • Guardianship: petitioner asks for guardianship; respondent is the proposed ward (or the ward's representative)
  • Name changes: petitioner asks for the change

Why different terms? Historical custom. These kinds of cases evolved out of equity courts (with their own vocabulary) rather than common-law courts (with the plaintiff/defendant tradition). The substance is the same.

A divorce case might be styled In re Marriage of Smith and Jones or Smith v. Jones. The petitioner (the one who filed for divorce) is named first.

Appeals: appellant and appellee

When a case is appealed, the parties get new names while the appeal is pending.

  • The appellant is the side that lost at the trial court and is asking the appellate court to reverse.
  • The appellee is the side that won at the trial court and wants the appellate court to affirm.

Sometimes the original case caption stays the same throughout the appeal. So if Smith sued Jones, won at trial, and Jones appealed, the case might still be styled Smith v. Jones: but Jones is now the appellant and Smith is now the appellee.

Some courts flip the caption to put the appellant first: Jones v. Smith in the appellate court. Conventions vary.

In the U.S. Supreme Court, the party seeking review is sometimes called the petitioner (because Supreme Court review is technically by petition for writ of certiorari). The other side is the respondent.

Cross-claims, counterclaims, and third-party claims

Cases get more complicated when defendants bring their own claims:

  • Counterclaim: a claim the defendant brings against the plaintiff in the same case. For purposes of the counterclaim, the defendant is essentially a plaintiff (with the burden of proof for the counterclaim) and the plaintiff is essentially a defendant.
  • Crossclaim: a claim one defendant brings against another defendant in the same case (when there are multiple defendants).
  • Third-party complaint: when a defendant brings in a new party who they say is responsible for the plaintiff's harm. The new party is a "third-party defendant."

You can see how a case with three or four parties can have someone playing multiple roles at once. Procedurally, each claim has its own plaintiff (the side bringing it) and defendant (the side defending it).

"In re" and "ex parte"

Some case styles don't follow the "X v. Y" pattern at all.

In re is Latin for "in the matter of." Used when the case doesn't have two adversarial parties:

  • In re Estate of Williams: probate proceeding
  • In re Smith: bankruptcy
  • In re Adoption of Doe: adoption

Ex parte means "from one side only." Used when the proceeding has only one party present (e.g., applications for emergency restraining orders, search warrants):

  • Ex parte Smith

These cases still have parties, but the styling reflects that they're not pure adversarial disputes.

Multiple parties on one side

Cases often have multiple plaintiffs or defendants. The case might be styled Smith and Jones v. Acme Corporation, or might just name the lead plaintiff: Smith et al. v. Acme Corporation. ("et al." is Latin for "and others.")

Class actions have a few named representative plaintiffs but represent the interests of many class members:

  • Smith v. Acme Corporation (class action): Smith is the named plaintiff representing the class.

When you're confused about who's who

Practical tips:

  1. Look at the caption. The case name and parties are listed at the top of every filing. The caption tells you exactly who's listed where.

  2. Look at the original complaint or petition. Whoever filed the opening document is the plaintiff/petitioner.

  3. Read the court rules. Different courts have different conventions. The rules will explain what to call parties in that court.

  4. Ask the clerk's office. They can tell you what role you're in based on how the case was filed.

If you're a pro se party, knowing your role matters because deadlines, formats, and obligations are often different for plaintiffs and defendants.

Why so many different names?

The variation reflects the historical development of different kinds of courts. English law had separate courts for common-law disputes (with plaintiffs and defendants) and equity disputes (with petitioners and respondents). Criminal courts had their own conventions because the government, not a private person, brought the case. Family law and probate courts inherited the equity terminology.

The U.S. legal system inherited all of these traditions and merged most courts into single trial courts handling both common-law and equity matters. But the vocabulary stuck.

You don't have to memorize all this. The key is recognizing that "plaintiff" and "petitioner" play similar roles (the side starting the case) and "defendant" and "respondent" play similar roles (the side defending). When in doubt, ask.

This lesson is research and educational information, not legal advice. The terminology in your specific case depends on the type of case and the local conventions of your court.