There Are Two Categories of Parties

A personal injury case is a civil lawsuit. In every civil lawsuit, there is at least one plaintiff and at least one defendant.


The plaintiff is the party who files a lawsuit. There can be one or more plaintiffs. This person or group claims someone else caused them harm. The plaintiff presents evidence to try to prove the other party is liable for their damages. Their damages are their physical, emotional, and financial injuries.


The defendant is the party who allegedly caused the plaintiff harm. There can be one or more defendants. They can be individuals, businesses, municipalities, or government agencies. The defendant doesn’t have to prove they didn’t cause the plaintiff harm. The burden of proof is on the plaintiff. But the defendant also presents evidence to counter the plaintiff’s allegations.

The Plaintiff Has the Burden of Proof

The plaintiff has to prove the defendant is liable for their injuries. The plaintiff must present evidence to the jury of the defendant’s negligent or harmful conduct. This is known as having the burden of proof. Different types of lawsuits have different burdens of proof. That means there are different standards plaintiffs have to meet. In a civil personal injury lawsuit, the plaintiff must prove the defendant caused them harm by a preponderance of the evidence. This level of proof means it is more likely than not that the defendant is responsible.

When There Are Many Plaintiffs

When there are many plaintiffs who suffer the same or similar injury, this changes the structure of the lawsuit. Many plaintiffs can mean dozens, hundreds, or thousands of people.

Class Actions

When there are many plaintiffs, the lawsuit may become a class action. One person or a small group of people and their lawyers ask the court to certify a class. By certifying a class, the court defines who is or is not a plaintiff in the class action lawsuit. One plaintiff becomes the class representative and is involved in the lawsuit.

Many plaintiffs in the class are not involved. They receive notice of the lawsuit. They can opt in or out. If they opt out, they don’t receive a part of the settlement or court verdict. Plaintiffs who are part of the class action might receive a small portion of the recovery.

Mass Torts

Mass torts involve numerous plaintiffs, but they are not the same thing as a class action lawsuit. A class action is one lawsuit on behalf of many plaintiffs. Mass torts are separate lawsuits by plaintiffs with similar injuries.

During mass tort claims, many plaintiffs may be represented by one firm. Law firms might share information and resources. Also, many of the lawsuits will be moved to the same court venue.

Adding Parties to a Lawsuit

After a plaintiff files a lawsuit against a defendant, more parties might join the lawsuit. New York’s Civil Practice Law and Rules control when parties must or can be added to lawsuits. Sometimes, adding parties is necessary. Other times, adding parties is for the best, but the lawsuit could continue without them.

Necessary Joinder of Parties

There might be a party who must be in the lawsuit for the issue to be resolved properly. A necessary party can be a plaintiff or defendant. If the court has jurisdiction over the party, they can be summoned to court. If the court doesn’t have jurisdiction, and the party won’t join voluntarily, the court must decide whether the case can continue. A judge can dismiss a case if a necessary party is missing.

Permissive Joinder of Parties

There might be parties who don’t have to join the lawsuit, but it makes sense for them to. A court might allow new plaintiffs or defendants to join the personal injury claim if it would efficiently resolve the issues. The new plaintiffs or defendant’s issues must come from the same set of circumstances as the current plaintiff and defendant.

Impleading a Third-Party Defendant

A defendant might claim another party is liable to them for all or part of the plaintiff’s allegations. When the new person is not already part of the lawsuit, the defendant can ask to bring them in. The court decides whether a third party can become involved in the case. The defendant files a claim against the third party. The original defendant becomes a third-party plaintiff. The new party becomes the third-party defendant.


If the lawsuit involves a monetary fund or property, someone outside of the lawsuit might have an interest in what happens to that fund or property. That person might ask to join the lawsuit to have a say in what happens to that fund or property.

Intervener (Intervention by Permission or as of Right)

A party might want to join a lawsuit voluntarily. This party must ask the court permission to join. They must show the judge they have a right to be involved. Sometimes, a party has the right to join a lawsuit without the court’s permission. For example, a government entity has the right to join a lawsuit if it contains a question of constitutional law.

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Are You Party to a Personal Injury Lawsuit?

If you have been injured or are somehow involved in a personal injury claim, call Hecht, Kleeger & Damashek, P.C. at (212) 490-5700, or reach out through our online contact form. We have years of experience handling personal injury lawsuits. We understand how parties become part of a lawsuit. We realize you might be a party to a lawsuit even if you weren’t the person hurt or the person who directly caused the accident. Talk with us about your part in the personal injury lawsuit.

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