Multidistrict Litigation (MDL)

Multidistrict litigation, or MDL, is how federal courts handle large numbers of similar cases filed in different districts. Instead of hundreds of judges each overseeing discovery on the same product, one judge handles the shared pretrial work: document exchanges, depositions of company witnesses, expert challenges, and settlement talks.

The process is set by 28 U.S.C. 1407. The Judicial Panel on Multidistrict Litigation, a group of federal judges, decides whether cases share common questions of fact and whether centralizing them will serve the convenience of the parties and witnesses and promote just and efficient conduct of the cases. If so, it picks a court and judge and assigns an MDL number. Under 28 U.S.C. 1407(a), each transferred case must be sent back to its original court at or before the end of pretrial proceedings unless it has already ended. In practice, most MDL cases resolve through settlement before that happens.

An MDL is not a class action. Each plaintiff keeps an individual case with individual damages, which is why MDLs are used for drug, device, and toxic exposure injuries where harms differ from person to person. Judges often schedule bellwether trials, test cases whose outcomes help both sides value the rest. Large MDLs can include thousands or even hundreds of thousands of plaintiffs, such as the 3M earplug litigation, which settled in 2023 for $6 billion.

To join an MDL, you file your own lawsuit, usually through a lawyer, and it is transferred in or filed directly under the court's orders. See what an MDL is, class actions versus mass torts, and the hair relaxer and AFFF MDLs, plus the bellwether trial entry.