Legal Guides
MDL vs. Class Action: How the Two Federal Procedures Differ
An MDL coordinates separate federal lawsuits for pretrial work under 28 U.S.C. 1407; a class action is one certified lawsuit that binds the class.
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Multidistrict litigation and class actions are two different federal procedures. An MDL moves separate lawsuits sharing common questions of fact into one district for coordinated pretrial proceedings under 28 U.S.C. 1407, and each case keeps its own identity. A class action is a single lawsuit, certified under Federal Rule of Civil Procedure 23, in which named plaintiffs represent a defined class and the judgment binds class members who do not opt out. The Judicial Panel on Multidistrict Litigation (JPML) decides MDL questions; a district judge decides class certification.
The short answer: an MDL is not a class action
Section 1407(a) lets civil actions involving common questions of fact, pending in different districts, be transferred to one district for coordinated or consolidated pretrial proceedings. The same provision requires each transferred action to be remanded to the district it came from at or before the end of those proceedings, unless the case has already ended. The cases stay separate. A class action is the opposite: one lawsuit, brought by a few plaintiffs for a group, that once certified resolves the claims of class members who do not opt out.
How the Panel creates an MDL
The JPML is seven sitting federal judges appointed by the Chief Justice, no two from the same circuit, and four must concur for any Panel action (28 U.S.C. 1407(d)). It decides whether actions in different districts share common questions of fact, and which judge and court will run the proceedings. Under 1407(c), proceedings begin on the Panel’s own initiative or on a party’s motion, with notice and a hearing.
After transfer, the Panel exercises what a Federal Judicial Center pocket guide calls virtually no further control over the cases. The transferee judge has all the powers of the court that sent the case, except that the judge does not conduct the trial (FJC, Ten Steps to Better Case Management, 2014).
What a class action requires under Rule 23
Rule 23(a) sets four prerequisites: the class is so numerous that joining all members is impracticable; there are questions of law or fact common to the class; the representatives’ claims or defenses are typical of the class; and the representatives will fairly and adequately protect the class. Rule 23(b) adds one of three further findings; for damages cases the usual route is 23(b)(3), which requires that common questions predominate over individual ones and that a class action be superior to other methods. Rule 23(c)(1)(A) requires the court to decide at an early practicable time whether to certify, and the certification order defines the class and appoints class counsel under Rule 23(g).
For a 23(b)(3) class the court directs the best notice practicable, including individual notice to members who can be identified through reasonable effort. Rule 23(c)(2)(B) requires the notice to state that the court will exclude any member who asks to be excluded and to explain the binding effect of a class judgment. Rule 23(c)(3)(B) provides that the judgment includes those notified who did not request exclusion.
Side-by-side differences
| Feature | Multidistrict litigation | Class action |
|---|---|---|
| Governing authority | 28 U.S.C. 1407 | Federal Rule of Civil Procedure 23 |
| Who decides the structure | JPML (seven federal judges) | The district judge hearing the case |
| What is combined | Pretrial proceedings only | The whole case, through judgment |
| Individual cases | Each plaintiff keeps a separate case | One case for the entire class |
| How a person takes part | By filing their own lawsuit | By falling within the class definition |
| Leaving the group | No class to leave | (b)(3) members may request exclusion |
| Effect of judgment | Binds only the parties to that case | Binds members who do not opt out |
Two examples on this site are MDLs rather than classes: the Roundup products liability litigation (MDL No. 2741, Northern District of California) and the AFFF firefighting foam litigation (MDL No. 2873, District of South Carolina). The rideshare passenger safety claims were centralized by the Panel as MDL No. 3084 and MDL No. 3171, both in the Northern District of California. MDLs also reach medical devices, as in the hernia mesh litigation. General explainers are on the Legal Guides hub, and the step-by-step version is in how mass tort litigation works.
What is established vs. what is disputed
Established by the governing text: how an MDL is created and ended under 1407, and how a class is certified and its members bound under Rule 23. Established by the Panel’s own record: its report dated September 1, 2026 lists 166 MDL dockets with 206,182 actions pending. Disputed case by case: whether a proposed class meets predominance and superiority under 23(b)(3), and whether a set of claims fits either device. The Advisory Committee notes to Rule 23 state that a mass accident injuring numerous people is ordinarily not appropriate for a class action, because damages and liability questions affect individuals differently.
Where the rules and records live
The JPML publishes its rules, its Panel orders, and monthly pending-MDL reports, including lists by district and by MDL number. Dockets and filings are in PACER. The text of 28 U.S.C. 1407 and of Rule 23 is published by the Cornell Legal Information Institute.
Key dates
- 1937: the earliest Advisory Committee notes accompanying Rule 23 are dated 1937 (Cornell LII, Rule 23).
- July 1, 1966: Rule 23 was substantially amended, producing the modern structure of prerequisites in (a) and categories in (b) (Cornell LII).
- April 29, 1968: Pub. L. 90-296 added 28 U.S.C. 1407, creating the JPML (Cornell LII; JPML, About the Panel).
- 2005: the Class Action Fairness Act increased the number of class actions in federal court and called for judicial best practices (FJC, Managing Related Proposed Class Actions, 2018).
- December 29, 2022: 1407 was amended by Pub. L. 117-328 (Cornell LII, 1407).
- September 1, 2026: the JPML pending-docket report listed 166 MDL dockets holding 206,182 actions.
What this does not establish
Nothing here decides any claim. Creating an MDL is not a finding that a product or party caused harm. A certification order decides only that Rule 23’s requirements are met at that time, and Rule 23(c)(1)(C) allows it to be altered or amended before final judgment. A transfer order decides only that common questions of fact make coordination convenient. Cases that do not settle can be remanded and tried on their own facts.
Frequently asked questions
Is an MDL the same as a class action?
No. An MDL groups separate federal lawsuits for pretrial proceedings under 28 U.S.C. 1407, and each case remains its own. A class action is one certified lawsuit that resolves the claims of members who do not opt out.
Do I have to do anything to be part of an MDL?
Yes. An MDL is composed of individually filed lawsuits. A person who wants to be a party files their own case, which can then be transferred into the centralized proceeding. There is no automatic inclusion.
Can a person opt out of an MDL?
Opting out is a class-action concept: in an MDL there is no class to leave, because each plaintiff is a party to their own case. Whether to accept the terms offered in a case is a decision for that plaintiff.
Who decides whether cases are consolidated, and can that decision be appealed?
The JPML decides. Section 1407(e) permits review of Panel orders only by extraordinary writ under 28 U.S.C. 1651, and bars any appeal or review of an order denying transfer.
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. *Cornell Law School, Legal Information Institute*: "Rule 23. Class Actions" ([link](https://www.law.cornell.edu/rules/frcp/rule_23), 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. *Federal Judicial Center*: "Managing Related Proposed Class Actions in Multidistrict Litigation" ([link](https://www.fjc.gov/sites/default/files/materials/21/Managing_Related_Proposed_Class_Actions_in_Multidistrict_Litigation.pdf), 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. *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)CollectiveClaim.us publishes general legal information. This article is not legal advice and does not create an attorney–client relationship. Court records and agency actions change; verify current status with the court or agency before relying on it.