What Is an MDL (Multidistrict Litigation)?

What Is an MDL?

Multidistrict Litigation (MDL) is a special federal legal procedure used to consolidate multiple civil lawsuits that share common factual questions into a single federal court for coordinated pretrial proceedings. MDLs are authorized by 28 U.S.C. § 1407, a federal statute enacted in 1968.

The purpose of an MDL is efficiency. When hundreds or thousands of people file separate lawsuits against the same defendant(s) over the same product, drug, or event, it would be wasteful for every court across the country to independently handle the same discovery, expert testimony, and pretrial motions. An MDL consolidates these common tasks before a single experienced judge, saving time and judicial resources while ensuring consistent rulings.

Crucially, an MDL is not a class action. In an MDL, each plaintiff maintains their own individual lawsuit with their own unique facts, injuries, and damages. The cases are only consolidated for pretrial purposes — once those proceedings are complete, cases that have not settled can be sent back to their original courts for individual trials.

As of 2025, MDLs account for a significant portion of the entire federal civil caseload. Major active MDLs include the Roundup weed killer litigation (MDL 2741), the AFFF firefighting foam litigation (MDL 2873), and numerous pharmaceutical and medical device MDLs.

How MDLs Are Created (The JPML)

The process of creating an MDL begins with the Judicial Panel on Multidistrict Litigation (JPML), a special body of seven sitting federal judges appointed by the Chief Justice of the United States. The JPML has the exclusive authority to transfer civil actions to a single district for coordinated pretrial proceedings.

An MDL transfer can be initiated in several ways:

The JPML then holds a hearing (typically during one of its regularly scheduled sessions held roughly every two months at rotating locations across the country) to determine whether consolidation is appropriate. The panel must find that:

If the JPML approves consolidation, it selects a transferee court and transferee judge — the federal district and judge who will oversee all pretrial proceedings. The selection is based on the judge's expertise, the geographic distribution of cases, and the court's available resources.

What Happens in an MDL

Once cases are transferred to the MDL, the transferee judge manages coordinated pretrial proceedings. This process typically follows a structured path that can span several years:

Plaintiffs' leadership: Early in the MDL, the transferee judge appoints a leadership structure — typically lead counsel, co-lead counsel, and a plaintiffs' steering committee (PSC). These attorneys make strategic decisions on behalf of all plaintiffs in the MDL, manage discovery, and negotiate with defendants. Individual plaintiffs still have their own attorneys, but the PSC handles MDL-wide work.

Coordinated discovery: The discovery process — document production, depositions, expert reports — is conducted once for all cases in the MDL, rather than being repeated in each individual case. This is where the efficiency gains are most significant.

Bellwether trials: The judge typically selects a small number of representative cases (called bellwether trials) to be tried before a jury. The results of these trials help both sides evaluate the strengths and weaknesses of the overall litigation and often drive global settlement negotiations.

Resolution: Most MDLs ultimately resolve through a global settlement. If no global settlement is reached, individual cases can be remanded (sent back) to their original courts for individual trials.

MDL vs. Class Action

MDLs and class actions are often confused, but they are fundamentally different legal mechanisms. Understanding the distinction is important for anyone considering joining a mass tort lawsuit. For a full comparison, see our guide to class action vs. mass tort.

Current Major MDLs

Dozens of significant MDLs are currently active in federal courts across the country. Here are some of the largest and most notable as of 2025:

Each of these MDLs involves a different product or exposure but follows the same general procedural framework under 28 U.S.C. § 1407. The transferee judge in each MDL has significant discretion in how they manage the proceedings, which is why the experience and judicial philosophy of the assigned judge can materially affect outcomes.

Your Individual Case in an MDL

If your case becomes part of an MDL, here is what you should know about how it affects you personally:

If you believe you have a potential mass tort claim, the first step is to consult with an attorney who can evaluate whether your case belongs in an existing MDL or should be filed independently. Most mass tort attorneys offer free initial consultations and work on a contingency fee basis.