How Mass Tort Litigation Works: From Filing to Resolution

“Mass tort” is a general label rather than a term defined in a single statute. It describes large numbers of individual injury claims sharing a common factual core, such as one drug or one device. In federal court most such claims are managed as multidistrict litigation (MDL) under 28 U.S.C. 1407, which centralizes cases for pretrial work without merging them. Each plaintiff keeps a separate case, and no step decides collectively that a product caused anyone’s injury.

What “mass tort” means

The Judicial Panel on Multidistrict Litigation (JPML) describes its docket as covering “mass torts, such as those involving asbestos, drugs and other products liability cases,” alongside antitrust, securities, and data-breach matters. What unites those categories is volume plus a common question of fact, the condition 28 U.S.C. 1407 addresses. The statute covers only federal civil actions pending in different districts, so the term reaches beyond what an MDL can hold. For the comparison with class actions, see MDLs versus class actions.

The path a claim usually takes

1. Individual lawsuits are filed. A federal civil action begins when a party files a complaint, pays the filing fee (waivable on a showing of inability to pay), serves the defendant, and asks the court for relief (U.S. Courts, Civil Cases).
2. A motion to centralize is filed. Under 1407(c), proceedings start on the Panel’s own initiative or on a party’s motion, with notice and a hearing.
3. The JPML decides. It weighs whether the actions share common questions of fact and whether transfer will serve the convenience of parties and witnesses and promote the just and efficient conduct of the actions, then selects the transferee court and judge.
4. Cases transfer and pretrial work begins. Discovery and pretrial motions are handled once for the group.
5. Representative cases may be tried. A court may try a few bellwether cases first.
6. The group resolves, or cases return home. Section 1407(a) requires remand of actions not terminated, at or before the end of centralized pretrial proceedings.

Who decides whether cases are centralized

The JPML is seven sitting federal judges appointed by the Chief Justice; no two may come from the same circuit, and four must concur for any Panel action (1407(d)). Review is limited: 1407(e) allows review only by extraordinary writ under 28 U.S.C. 1651, and there is no appeal of a denial of transfer. The Panel describes the purpose of centralization as avoiding duplication of discovery, preventing inconsistent pretrial rulings, and conserving the resources of the parties, their counsel, and the judiciary.

What the transferee judge manages

After transfer the Panel largely steps back: a Federal Judicial Center (FJC) guide states that it exercises virtually no further control over the cases, and that the transferee judge has all the powers of the transferor court except conducting the trial. The judge resolves motions to dismiss, rules on challenges to expert testimony, and can organize plaintiffs’ counsel. A class-certification motion can arise inside an MDL, but no class has to be certified.

Bellwether trials

Courts sometimes select a small set of cases for early trial. A bellwether verdict binds only the parties to that case, but it informs both sides about how juries may respond, which can shape settlement talks.

How mass tort cases end

• Settlement. Many MDLs resolve through a settlement program negotiated for the group, and each plaintiff decides whether to accept the terms offered in their own case. A class settlement differs: Rule 23(e) requires court approval after a hearing and a finding that the proposal is fair, reasonable, and adequate.
• Dismissal. Courts can end cases by dismissal or summary judgment, including orders excluding a plaintiff’s expert evidence.
• Remand and trial. Because 1407(a) requires remand of actions not terminated, unsettled cases return to the districts where they were filed for trial.

Not every large group of claims is resolved this way. State-court claims are not transferred into a federal MDL; some are coordinated in state courts, and others resolve in bankruptcy.

Where the authoritative rules and records live

The JPML publishes its rules, its Panel orders, and monthly pending-MDL reports by district and by MDL number. The statute governing centralization, 28 U.S.C. 1407, and the text of Federal Rule of Civil Procedure 23 are published by the Cornell Legal Information Institute. The FJC keeps a listing of its MDL pocket guides. General explainers are collected on the Legal Guides hub.

What is established vs. what is alleged

Established, from the Panel’s own record: the JPML’s calendar-year 2025 statistics record products liability as the largest category of pending MDLs at December 31, 2025 (61 dockets, 38%), ahead of antitrust (36 dockets, 23%) and data breach and consumer privacy (20 dockets, 13%). Its pending-docket report dated September 1, 2026 lists 166 MDL dockets with 206,182 actions pending, and shows concentration: 21 MDLs with 1,000 or more pending actions accounted for 194,835 actions (94.5%). Examples on this site include the Depo-Provera litigation (MDL No. 3140, Northern District of Florida) and the Paraquat litigation (MDL No. 3004).

Alleged, not decided: the merits of any claim. A complaint asserts that a product or party caused harm, a transfer order asserts only that common questions of fact exist, and a bellwether verdict decides one case. None of these is a court finding, binding on a plaintiff group, that a product caused a disease. The hernia mesh litigation shows that more than one MDL can cover related products, including MDL No. 2846 in the Southern District of Ohio.

Key dates

• April 29, 1968: Pub. L. 90-296 added 28 U.S.C. 1407, creating the JPML (Cornell LII; JPML, About the Panel).
• January 1, 2014: the FJC and the JPML published the second edition of Ten Steps to Better Case Management (FJC).
• December 29, 2022: 1407 was amended by Pub. L. 117-328 (Cornell LII).
• September 1, 2026: the JPML pending-docket report listed 166 MDL dockets and 206,182 actions.

What this does not establish

Nothing here decides any claim. An MDL transfer order is a procedural ruling about common facts, not a finding of causation or liability. A bellwether verdict or a settlement in one case does not bind or set the value of another plaintiff’s case. The figures above are counts of cases on a docket, not assessments of their merit.

Frequently asked questions

Is joining an MDL the same as joining a class action?

No. An MDL consists of separate lawsuits centralized for pretrial work under 28 U.S.C. 1407. A class action is a single lawsuit certified under Federal Rule of Civil Procedure 23 that binds class members who do not opt out.

Does an MDL decide whether a product caused an injury?

No. Centralization addresses coordination, not causation. Product-defect and general-causation questions are decided, if at all, through the ordinary pretrial process, including rulings on expert evidence and any trials.

What happens to cases that do not settle?

Section 1407(a) requires the Panel to remand actions that were not terminated, at or before the conclusion of the centralized pretrial proceedings. Remanded cases return to the district where they were filed, where trial may follow.

Sources

1. *United States Judicial Panel on Multidistrict Litigation*: "About the Panel" ([link](https://www.jpml.uscourts.gov/about-panel), accessed 2026-10-13) 2. *United States Judicial Panel on Multidistrict Litigation*: "Pending MDLs" ([link](https://www.jpml.uscourts.gov/pending-mdls-0), accessed 2026-10-13) 3. *United States Judicial Panel on Multidistrict Litigation*: "MDL Statistics Report: Distribution of Pending MDL Dockets by District (September 1, 2026)" ([link](https://www.jpml.uscourts.gov/sites/jpml/files/Pending_MDL_Dockets_By_District-September-1-2026.pdf), accessed 2026-10-13) 4. *United States Judicial Panel on Multidistrict Litigation*: "Calendar Year Statistics, January through December 2025" ([link](https://www.jpml.uscourts.gov/sites/jpml/files/JPML_Calendar_Year_Statistics-CY-2025%201-16-26-Final_0.pdf), accessed 2026-10-13) 5. *Cornell Law School, Legal Information Institute*: "28 U.S. Code 1407 - Multidistrict litigation" ([link](https://www.law.cornell.edu/uscode/text/28/1407), accessed 2026-10-13) 6. *Cornell Law School, Legal Information Institute*: "Rule 23. Class Actions" ([link](https://www.law.cornell.edu/rules/frcp/rule_23), accessed 2026-10-13) 7. *Federal Judicial Center*: "Ten Steps to Better Case Management: A Guide for Multidistrict Litigation Transferee Judges, Second Edition" ([link](https://www.fjc.gov/content/ten-steps-better-case-management-guide-multidistrict-litigation-transferee-judges-second), accessed 2026-10-13) 8. *Federal Judicial Center*: "Multidistrict Litigation (MDL) publication listing" ([link](https://fjc.gov/subject/multidistrict-litigation-mdl), accessed 2026-10-13) 9. *Administrative Office of the U.S. Courts*: "Civil Cases" ([link](https://www.uscourts.gov/about-federal-courts/types-cases/civil-cases), accessed 2026-10-13)

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