A party in a lawsuit is any person, company, or entity that is formally named in a legal case and bound by the court’s decisions. This single fact shapes everything about how a lawsuit works, who bears legal risk, and who can collect a settlement.
Most people first encounter this term when they get served papers or when a class action notice lands in their inbox. Both situations raise the same urgent questions: what does this mean for me, and what do I have to do now?
This guide breaks down every type of party in a lawsuit, from plaintiffs and defendants to intervening parties and class action members. You’ll also learn what rights and responsibilities attach to each role and how party status can change mid-case.
One fact worth knowing upfront: in U.S. federal courts, the rules governing who can be a party are set out in the Federal Rules of Civil Procedure, specifically Rules 17 through 25.
What Is a Party in a Lawsuit?
A party in a lawsuit is any individual, business, government agency, or legal entity that is officially named in court proceedings and has legal standing to participate in the case.
Being a party is not the same as being a witness or a bystander. Parties have skin in the game. They can win, lose, owe money, or receive money based on the court’s final ruling.
Courts treat the term broadly. A party can be a single person suing their neighbor. It can be a Fortune 500 company defending a product liability claim. It can even be a government agency, like the Federal Trade Commission, pursuing a corporate defendant.
| Role | Who It Is | What They Stand to Gain or Lose |
|---|---|---|
| Plaintiff | Person or entity bringing the claim | Potential money damages or court relief |
| Defendant | Person or entity being sued | Financial liability, injunctions, or court orders |
| Third Party | Outside party brought in by defendant | Potential shared liability |
| Intervenor | Party that joins mid-case | Protects their own legal interests |
| Class Member | One of many similarly affected people | Pro-rata share of settlement funds |
The court’s jurisdiction over a party begins the moment that party is served with legal process or files their own documents with the court.
Types of Parties in a Lawsuit
There are several distinct types of parties in a lawsuit, and each one plays a different role in how the case proceeds and resolves.
Understanding which type of party you are determines what papers you must file, what deadlines apply to you, and what you can actually get out of the case.
The main types include:
- Plaintiff: The party who files the lawsuit and seeks relief
- Defendant: The party being sued, who must respond or face a default judgment
- Third-Party Defendant: A new party brought into the suit by the original defendant
- Intervenor: A party who wasn’t originally named but asks the court to join
- Cross-Claimant: A defendant who sues another defendant in the same case
- Counterclaimant: A defendant who sues the plaintiff back within the same action
- Class Action Members: A large group of people treated as one collective party
Think of a lawsuit like a chess game. The plaintiff makes the first move. The defendant responds. But mid-game, new pieces can enter the board.
Each party type has different filing deadlines, different discovery obligations, and different exposure to court orders.
Plaintiff and Defendant in a Lawsuit
The plaintiff is the party who starts a lawsuit by filing a complaint, while the defendant is the party who must respond to that complaint in court.
These two roles are the foundation of every civil lawsuit in the American legal system.
The Plaintiff’s Job:
The plaintiff carries the burden of proof. That means they must show evidence to support their claims. In civil cases, the standard is “preponderance of the evidence,” meaning more likely than not.
The Defendant’s Job:
The defendant must file a formal answer to the complaint, usually within 21 days in federal court or 30 days in most state courts. Failing to respond can lead to a default judgment, which means the plaintiff wins automatically.
| Detail | Plaintiff | Defendant |
|---|---|---|
| Who starts the case | Yes | No |
| Burden of proof | Yes | No (in civil cases) |
| Response deadline | N/A | 21 to 30 days after service |
| Risk if they do nothing | Case gets dismissed | Default judgment entered against them |
| Can they countersue | No (separately) | Yes, as a counterclaimant |
Both parties have the right to legal representation, the right to present evidence, and the right to appeal an unfavorable verdict.
Key Takeaway: The plaintiff starts the case and bears the proof burden; the defendant must respond on time or face automatic loss.
Third Party in a Lawsuit
A third party in a lawsuit is someone who was not originally named in the complaint but gets pulled into the case by one of the existing parties, most often the defendant.
This is a common legal move. Say you slip and fall at a store. You sue the store (defendant). The store then argues the cleaning company it hired is actually responsible. The store files a “third-party complaint” against the cleaning company. Now the cleaning company is a third-party defendant.
Third-party practice exists under Rule 14 of the Federal Rules of Civil Procedure.
Why defendants bring in third parties:
- To shift liability to someone else
- To share liability across multiple responsible parties
- To recover indemnification if they end up paying damages
The third-party defendant has the same rights as any other defendant once named. They can defend the claims, file their own cross-claims, or even bring in a fourth party.
| Aspect | Detail |
|---|---|
| Rule governing it | FRCP Rule 14 |
| Who files the third-party complaint | The original defendant |
| What the third party can do | Defend, cross-claim, or implead others |
| Common contexts | Contractors, manufacturers, insurers |
Named Party in a Lawsuit
A named party in a lawsuit is someone whose full legal name appears directly in the court documents as either a plaintiff or defendant, as opposed to unnamed or “Doe” defendants or absent class members.
Being named matters enormously. It means the court has personal jurisdiction over you specifically. It means your name appears on the public record. It means court orders can be directed at you personally.
In class actions, only the lead plaintiffs and named defendants appear on the record. The thousands of other class members participate without being individually named.
Why being named differs from being unnamed:
- Named parties receive all court filings and notices directly
- Named parties must participate in discovery, producing documents and sitting for depositions
- Named parties are bound by any judgment, whether they win or lose
- Unnamed class members can often opt out and preserve their right to sue separately
If you receive legal papers with your name on them, you are a named party. That triggers real deadlines and real obligations.
Class Action Party
In a class action lawsuit, the parties include a small group of named lead plaintiffs, the named corporate defendant, and a large class of unnamed members who share the same legal claims.
Class actions exist because it would be impractical for thousands of people to each file their own lawsuit over the same product defect, data breach, or deceptive practice.
The named plaintiff, often called the class representative, acts on behalf of everyone in the class. Courts must certify the class under Rule 23 of the Federal Rules of Civil Procedure before the case can proceed as a class action.
How class membership works in practice:
- You may automatically become a class member based on your purchase history or exposure record
- You typically receive a notice in the mail or by email when a class is certified
- You usually have a deadline to opt out if you want to keep your right to sue independently
- If you stay in, you share in any settlement but give up the right to sue separately
| Class Action Party Type | Role |
|---|---|
| Named Lead Plaintiff | Files suit, represents the class, appears in court |
| Class Members | Benefit from settlement but don’t appear individually |
| Named Defendant | Company or entity being sued |
| Settlement Administrator | Third-party firm that processes claims and sends payments |
Settlement payouts for individual class members often range from $20 to several hundred dollars, depending on the case and the number of valid claims filed.
Key Takeaway: In a class action, most members are unnamed parties who benefit from the case without actively litigating it.
Real Party in Interest
The real party in interest is the person or entity who actually owns the legal right being enforced in a lawsuit, even if someone else is nominally listed as the plaintiff.
Under Rule 17 of the Federal Rules of Civil Procedure, every lawsuit must be prosecuted in the name of the real party in interest.
Here’s a practical example. An insurance company pays out a claim to a car accident victim. The insurance company then wants to sue the at-fault driver to recover that payout. The insurance company, not the original victim, is now the real party in interest. This legal process is called subrogation.
Why this concept matters:
- Courts can dismiss a case if the wrong party filed it
- Defendants can challenge whether the plaintiff has actual legal standing
- Executors, trustees, and guardians often file suits on behalf of others as the real party in interest
| Situation | Real Party in Interest |
|---|---|
| Insurance subrogation claim | Insurance company |
| Estate lawsuit after death | Executor or administrator |
| Minor child’s injury claim | Parent or legal guardian |
| Assigned debt lawsuit | Debt buyer, not original creditor |
Necessary Party vs Proper Party
A necessary party is someone who must be included in a lawsuit for the case to be resolved fairly, while a proper party is someone who may be included but whose absence won’t derail the case.
Rule 19 of the Federal Rules of Civil Procedure governs necessary parties, also called “required parties.” If a necessary party cannot be joined, the court may have to dismiss the entire lawsuit.
Think of it this way: if two siblings jointly own a piece of property and one sues over it, the other sibling is probably a necessary party. You can’t fully resolve the dispute without them in the room.
Proper parties, by contrast, are people whose involvement would be useful but not mandatory. Courts handle proper parties under Rule 20, which covers “permissive joinder.”
| Category | Must Be Included | Case Dismissed Without Them |
|---|---|---|
| Necessary (Indispensable) Party | Yes | Possibly yes |
| Necessary (Non-Indispensable) | Yes if possible | No, court proceeds |
| Proper (Permissive) Party | No | No |
Intervening Party in a Lawsuit
An intervening party is someone who was not originally part of a lawsuit but successfully asks the court for permission to join after the case has already started.
This is governed by Rule 24 of the Federal Rules of Civil Procedure. There are two types: intervention of right and permissive intervention.
Intervention of Right occurs when a party has a legally protected interest in the outcome of the case that existing parties can’t adequately represent. Courts must allow this.
Permissive Intervention occurs when a party shares a common legal question with the existing case but doesn’t have the same urgent stake. Courts have discretion to allow or deny it.
Real-world example: A state government might intervene in a lawsuit challenging the constitutionality of a state law, even if it wasn’t the original defendant.
| Type | Requires Court Permission | Standard |
|---|---|---|
| Intervention of Right | Must be granted if criteria met | Legally protected interest at stake |
| Permissive Intervention | Court has discretion | Common question of law or fact |
Key Takeaway: Intervening parties join mid-lawsuit to protect their own interests, and courts treat intervention of right very differently from permissive intervention.
Party in a Civil Lawsuit
A party in a civil lawsuit is any person, company, or entity involved in a non-criminal legal dispute, which includes personal injury cases, contract disputes, product liability claims, and class actions.
Civil lawsuits make up the vast majority of cases that everyday people encounter. When a consumer sues a pharmaceutical company over dangerous side effects, both are parties in a civil lawsuit.
The plaintiff in a civil case seeks money damages, an injunction, or specific performance. The defendant fights back or negotiates a settlement.
Common types of civil lawsuits and their parties:
- Product liability: Injured consumer vs. manufacturer
- Personal injury: Accident victim vs. at-fault party
- Contract dispute: Business vs. business or individual
- Class action: Class of consumers vs. corporate defendant
- Employment: Employee vs. employer
In civil cases, the losing party typically pays money. They don’t go to jail. That’s the key structural difference from criminal cases.
Civil lawsuit filing fees at the federal level start at $405 as of 2025, with state court fees varying widely by jurisdiction.
Party in a Criminal Lawsuit
In a criminal lawsuit, the parties are the government (federal or state) and the defendant, with the crime victim playing a separate but non-party role.
This is one of the biggest misconceptions people have about criminal cases. The victim is not technically a party. The state is. The prosecutor files charges on behalf of the people, not on behalf of the individual victim.
That’s why criminal case captions read “State of California v. John Smith” or “United States v. Jane Doe.” The government is always the plaintiff in a criminal case.
| Role | Criminal Case | Civil Case |
|---|---|---|
| Plaintiff | Government (state or federal) | Individual, company, or agency |
| Defendant | Accused person or entity | Person or company being sued |
| Standard of Proof | Beyond reasonable doubt | Preponderance of evidence |
| Possible Outcome | Imprisonment, fines, probation | Money damages, injunctions |
| Victim’s Role | Witness, not a party | Often the plaintiff |
A defendant in a criminal case has constitutional protections under the Fifth and Sixth Amendments. These don’t apply the same way in civil proceedings.
Adverse Party in a Lawsuit
The adverse party is simply the opposing side in a lawsuit: whoever you are up against in the legal action.
In a lawsuit between a plaintiff and a defendant, each is the other’s adverse party. The term gets used a lot in discovery rules and evidence law. For example, you can call an adverse party’s witness for cross-examination under different rules than your own witnesses.
This matters practically when requesting documents. Under the Federal Rules, a party can demand documents from their adverse party through discovery tools like interrogatories, requests for production, and depositions.
Key procedural rights triggered by adverse party status:
- Right to depose the adverse party’s witnesses
- Right to request all relevant documents the adverse party holds
- Right to demand written answers to interrogatories
- Right to submit requests for admission
The term “adverse party” shows up constantly in motion practice. When you file a motion, you serve a copy on the adverse party. When a settlement offer is made, it goes to the adverse party’s attorney.
Key Takeaway: Every lawsuit has adverse parties on opposite sides, and that status triggers specific discovery rights and procedural obligations.
How to Become a Party in a Lawsuit
You become a party in a lawsuit either by filing a complaint as a plaintiff, being served with a complaint as a defendant, or being brought in by the court or another party through third-party practice or intervention.
There’s no application process. The status attaches when you’re formally included in the legal proceedings.
Four ways you can become a party:
- File your own lawsuit. You become the plaintiff the moment you file a complaint with the court and pay the filing fee.
- Get served with papers. If someone sues you, you become a defendant upon service of process.
- Be joined by another party. An existing defendant can bring you in as a third-party defendant.
- Ask to intervene. You can file a motion to intervene if you have a stake in the outcome.
| Path to Party Status | Who Initiates | Timeframe |
|---|---|---|
| Filing a complaint | You | Immediate upon filing |
| Service of process | Opposing party | Upon delivery of summons |
| Third-party joinder | Existing defendant | After original answer filed |
| Intervention | You | Anytime during active litigation |
Statutes of limitations are critical here. Most personal injury claims must be filed within two years of the harm. Missing that window means you lose the right to become a plaintiff in that case.
Adding a Party to a Lawsuit
Adding a party to a lawsuit, called “joinder,” can happen voluntarily when parties agree or involuntarily when the court orders it or when an existing party files additional claims.
Rule 15 covers adding parties through amended pleadings. Rule 19 covers mandatory joinder of necessary parties. Rule 20 covers permissive joinder when it’s optional but allowed.
Courts will allow new parties to be added early in a case pretty freely. As the case ages and gets closer to trial, courts become more reluctant because adding new parties causes delays and disruption.
When courts allow party additions:
- Early in the case, before significant litigation activity
- When the new party’s claim or defense arises from the same transaction or event
- When justice requires it and no party is unfairly prejudiced
When courts refuse:
- Close to trial, when adding a party would force postponement
- When the new party raises entirely unrelated claims
- When the statute of limitations has run on the claims against the new party
The party seeking to add someone new typically files a motion for leave to amend their complaint, attaching the proposed amended complaint as an exhibit.
Removing a Party from a Lawsuit
A party can be removed from a lawsuit through voluntary dismissal, a court order, settlement of claims against that specific party, or a finding that they lack standing or were improperly named.
This happens more often than people think. Sometimes a plaintiff realizes they sued the wrong entity. Sometimes a named defendant settles before trial while the case continues against others.
Common ways a party exits a lawsuit:
- Voluntary dismissal: The party filing claims against them drops those claims under Rule 41
- Summary judgment: The court finds no genuine dispute exists as to that party’s claims
- Settlement: That specific party pays or resolves the claims against them
- Lack of standing: The court finds the party has no legal right to be in the case
- Substitution: One party is swapped for another, common in death or bankruptcy situations
| Exit Method | Who Decides | When It Happens |
|---|---|---|
| Voluntary Dismissal | Plaintiff | Any time (with or without prejudice) |
| Summary Judgment | Court | After discovery, before trial |
| Settlement | Both parties | Any stage |
| Standing Challenge | Court | Often early in the case |
A dismissal “with prejudice” means the claims are gone forever. A dismissal “without prejudice” means they can be refiled later within any remaining time limits.
Key Takeaway: Parties can exit lawsuits in multiple ways, and whether that exit is “with” or “without” prejudice determines whether the claims are gone for good.
Party Rights and Responsibilities in a Lawsuit
Every party in a lawsuit holds specific legal rights and carries specific legal responsibilities that attach the moment they become part of the case.
This is where most people get tripped up. They think being named in a lawsuit is passive. It’s not. It triggers a real set of obligations you must meet or risk serious consequences.
Core Rights of Every Party:
- Right to notice of all hearings and court filings
- Right to legal representation (though not court-appointed in civil cases)
- Right to present evidence and call witnesses
- Right to cross-examine the opposing party’s witnesses
- Right to appeal an unfavorable decision
Core Responsibilities of Every Party:
- Respond to the complaint within the court’s deadline
- Participate in discovery honestly and completely
- Preserve relevant documents, emails, and records once litigation is anticipated
- Appear for scheduled depositions and court dates
- Comply with court orders or face sanctions
Consequences of ignoring your responsibilities:
| Failure | Possible Consequence |
|---|---|
| Not responding to complaint | Default judgment against you |
| Destroying relevant evidence | Sanctions, adverse inference jury instruction |
| Missing a deposition | Contempt of court |
| Ignoring court orders | Case dismissal or default |
| Failing to pay judgment | Wage garnishment, bank levies, property liens |
Parties in federal court are also subject to Rule 11, which requires that every document filed in court be signed by an attorney certifying that the claims are legally and factually sound. Frivolous claims can result in financial penalties.
Frequently Asked Questions
What does it mean to be a party in a lawsuit?
Being a party in a lawsuit means your name is formally included in court proceedings and the court’s decisions can directly affect you legally and financially.
Parties are not the same as witnesses or bystanders. They have rights to present their case and obligations to participate in the legal process.
There are several types of parties, including plaintiffs, defendants, third-party defendants, and intervenors, each with different roles.
What is the difference between a plaintiff and a defendant?
The plaintiff is the party who files the lawsuit and seeks a legal remedy, while the defendant is the party being sued and must respond.
In civil cases, the plaintiff bears the burden of proving their claims by a preponderance of the evidence.
The defendant must file a formal response within the court’s deadline, typically 21 to 30 days after being served.
Can a company be a party in a lawsuit?
Yes, any legal entity, including corporations, LLCs, partnerships, and government agencies, can be a party in a lawsuit.
Companies can sue and be sued just like individuals. They must be represented by a licensed attorney in federal court.
Being a party as a company means the company’s documents, finances, and communications can be subject to discovery.
What happens if you ignore being named a party in a lawsuit?
If you are named as a defendant and do nothing, the court will likely enter a default judgment against you, meaning the plaintiff wins automatically.
A default judgment can result in wage garnishment, frozen bank accounts, or liens placed on your property.
Courts rarely overturn default judgments unless you can show a legitimate reason for missing the deadline and a valid defense to the claims.
How do you become a party in a class action lawsuit?
You typically become a class action member automatically when a class is certified and you fit the class definition, such as purchasing a specific product during a specific time period.
You’ll receive a class notice explaining your rights, including your deadline to opt out if you prefer to sue separately.
If you stay in the class, you share in any settlement without needing to hire your own attorney or appear in court.
Your Next Step
Understanding your status as a party in a lawsuit is step one. Whether you’ve been served with papers, received a class action notice, or are thinking about filing your own claim, knowing what type of party you are shapes every decision that follows.
Check your deadlines first. Response windows in civil cases are short and courts rarely grant extensions without good cause. Miss one, and your options narrow fast.
If your name is on court documents right now, treat it seriously. Your rights are real, your responsibilities are real, and so are the consequences of doing nothing
