What is MDL (multidistrict litigation)?

Congress created the MDL process in 28 U.S.C. 1407. The statute allows civil cases "involving one or more common questions of fact" that are pending in different federal districts to be transferred to any district for coordinated or consolidated pretrial proceedings, when doing so serves the convenience of parties and witnesses and promotes the just and efficient conduct of the cases.

The decision belongs to the Judicial Panel on Multidistrict Litigation (JPML). By statute, the JPML has seven federal circuit and district judges chosen by the Chief Justice, no two from the same circuit, and any action by the panel needs the agreement of four members. The panel picks the transferee court and the judge who will manage the litigation.

The key limit is in the same statute: transfer is for pretrial proceedings only. Each transferred case must be remanded to the district it came from at or before the end of pretrial proceedings unless it has already ended.

An MDL usually begins when a party in one of the scattered lawsuits files a motion with the JPML asking for centralization. The panel can also act on its own. It holds hearing sessions about six times a year (six in 2025) and then issues an order granting or denying transfer.

The panel does not grant every request. In calendar year 2025, 32 motions for centralization were filed with the JPML, 21 were granted, and 16 were denied, withdrawn, or found moot, according to the panel's annual statistics. Denials often happen when there are only a few cases, when the cases involve different products, or when the parties can coordinate informally.

Once an MDL exists, later-filed federal cases with the same facts are added as "tag-along" actions. The JPML reported 1,300 tag-along transfers in 2025. Lawsuits filed in state court are not part of a federal MDL, although state courts sometimes run their own consolidated proceedings in parallel.

After transfer, the MDL judge organizes the litigation. Common steps include:

1. Leadership appointments. The judge appoints a plaintiffs' steering committee and lead counsel to handle shared work, such as discovery from the company and expert witnesses.
2. Master pleadings and plaintiff fact sheets. Plaintiffs often file short-form complaints and fill out questionnaires about their use of the product and their injuries.
3. Discovery. Company documents and witness depositions are gathered once for everyone rather than in each case.
4. Expert challenges. The judge rules on whether each side's scientific experts can testify. These rulings can make or break an entire MDL.
5. Bellwether trials. The judge selects a small group of representative cases for early trials. The verdicts are not binding on anyone else, but they show how juries react.
6. Settlement or remand. Many MDLs end with a global settlement program; cases that do not settle can be sent back to their home courts for trial.

The baby food heavy metals MDL and the social media addiction MDL are examples of MDLs that were in pretrial proceedings as of September 2026. The JPML reported 483 pending cases in the baby food MDL (No. 3101) and 3,208 in the social media addiction MDL (No. 3047) on September 1, 2026.

As of September 1, 2026, the JPML's pending-docket report listed 166 active MDLs with 206,182 actions pending before 142 transferee judges in 50 districts. A handful of product cases hold most of those lawsuits. Here are several from that report that match topics people search for:

Not every MDL is a mass tort. According to the JPML's year-end 2025 figures, products liability accounted for 61 pending MDLs, antitrust for 36, and data breach and consumer privacy for 20. Data breach MDLs, like the Snowflake litigation that includes Ticketmaster customers, usually proceed as class actions inside the MDL.

People often confuse the two, but the difference changes what you need to do:

• In a class action, you are included automatically if you fit the class definition, and one settlement or judgment binds everyone who did not opt out.
• In an MDL of individual cases, you are only included if you file your own lawsuit, and any settlement offer is yours to accept or reject based on your own injuries.

An MDL can contain class actions, individual cases, or both. According to the JPML, 20 of the MDLs pending at the end of 2025 involved data breach and consumer privacy claims, which usually proceed as class actions inside the MDL. For a deeper comparison, see class action vs. mass tort.

MDLs tend to run for years. Expert rulings and bellwether trials alone can take two or more years after centralization, and large settlement programs take time to process claims. Some MDLs last for decades: the September 11, 2001 terrorist attacks litigation, MDL 1570, still had 372 pending actions on the JPML's September 1, 2026 report. For typical timelines, see how long lawsuits take.

If you think you have an injury tied to a product in an MDL:

• Check your deadline. The MDL does not pause your state's statute of limitations for a claim you have not filed.
• Gather records. Proof of use (pharmacy records, receipts, product packaging) and medical records of your diagnosis are the core of any claim.
• Expect individual scrutiny. MDL plaintiffs usually complete detailed fact sheets and may be asked to provide more records than a class member ever would.

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