Class action vs. mass tort: what is the difference?

A class action is governed by Federal Rule of Civil Procedure 23 in federal court, or a similar state rule. A lead plaintiff files on behalf of a defined group, and if the judge certifies the class, the case proceeds for everyone at once. For a damages class under Rule 23(b)(3), common questions must predominate over individual ones and a class action must be superior to other methods of resolving the dispute.

That predominance test is why class actions fit claims where the harm is the same for everyone: a fee everyone was charged, a label everyone saw, a breach that exposed everyone's data. Class members typically do nothing until a settlement notice arrives, then file a claim or get paid automatically. Examples include the Amazon returns settlement and the Flo Health data sharing settlement.

"Mass tort" is not a term defined in the federal rules. It describes a situation: many people injured by the same product, drug, device, or exposure, each bringing an individual claim for their own harm. Each plaintiff has their own lawyer (often one of a few firms representing thousands of clients), their own medical records, and their own damages.

When many federal cases share common facts, the Judicial Panel on Multidistrict Litigation can send them to one judge for pretrial work under 28 U.S.C. 1407. Cases transferred into an MDL are handled together only for pretrial proceedings, and each case must be sent back to its original court for trial unless it ends earlier. Judges often schedule bellwether trials, test cases that show both sides how juries value the claims, which frequently leads to a global settlement program.

Current examples include the hair relaxer cancer litigation, the Ozempic and GLP-1 litigation, and the AFFF firefighting foam litigation. These are allegations unless and until a court or jury rules otherwise. The JPML's September 1, 2026 report listed 12,129 pending cases in the hair relaxer MDL and 4,022 in the GLP-1 drug MDL.

A useful rule of thumb: if the harm is the same for everyone, it is usually a class action; if the harm depends on each person's body and medical history, it is usually a mass tort. Under the Class Action Fairness Act, a "mass action" in which the money claims of 100 or more people are proposed to be tried jointly can be moved to federal court much like a class action.

The Supreme Court drew this line in Amchem Products, Inc. v. Windsor, decided June 25, 1997. The parties had proposed a nationwide class to settle current and future asbestos claims for potentially hundreds of thousands of people. The Court rejected it, finding that differences in exposure, illness, and future risk meant common questions did not predominate and that the class representatives could not fairly represent both people who were already sick and people who were not.

Since then, courts have been cautious about certifying personal injury classes. Instead, injury claims move through MDLs and state court consolidations as individual cases. The Judicial Panel's own data shows how central these cases are. Products liability made up 61 of the MDLs pending on December 31, 2025, or 38% of all pending MDLs, the largest single category.

A class settlement creates one common fund, pays fees and costs out of it, and divides the rest among valid claims by a formula, often equal shares or tiers. Class payouts are usually modest because the individual harm is usually modest. In the FTC's 2019 study of consumer class settlements, half paid a median of $69 or more per claimant and a quarter paid a median of $200 or more. See how class action money is divided.

A mass tort settlement usually works differently. The defendant agrees to fund a program, and each plaintiff's award is based on factors like diagnosis, severity, age, and proof of use or exposure. Plaintiffs typically must submit medical records and proof of product use, and each person decides whether to accept. Lawyers are paid under each client's contingency agreement rather than through a single court-approved class fee, although MDL judges sometimes cap fees or order a share set aside for the lawyers who did common work.

Because awards are tied to individual injuries, a mass tort can pay far more per person than a consumer class action, but only to people who can document a qualifying injury.

If you got a settlement notice about a fee, a product label, or a data breach, you are probably in a class action. Read the notice, check the deadline, and file on the official settlement website if you want to be paid. Our open settlements list tracks current deadlines.

As of September 1, 2026, the JPML listed 166 pending MDLs, and none of them includes you unless you or your lawyer files a case. If you or a family member developed a serious illness or injury after using a drug, device, or product that is the subject of litigation, you are likely looking at a mass tort. That means:

• You will not be included automatically. You need your own claim, filed by a lawyer.
• Your deadline is personal. Each state sets a statute of limitations for injury claims, and it often runs from when you knew or should have known about the injury and its possible cause.
• Records matter. Keep pharmacy records, medical records, product packaging, and receipts.

A free case review takes about two minutes and connects you with independent attorneys who handle these cases. For more background, see what MDL means and class action vs. individual lawsuit.