1. What is an MDL or multidistrict litigation?

Multidistrict Litigation (MDL) is a special procedure where cases that share some common issues of fact are consolidated before one federal judge for the purpose of coordinating discovery and other pre-trial proceedings. MDLs differ from class action lawsuits in that all the cases remain separate cases, and ultimately are adjudicated individually in accordance with rulings established by the MDL court. The MDL system came about through an act of Congress in 1968 and was intended to streamline case management and avoid duplicative efforts by having one federal court handle all pre-trial matters. 

​

2. When did the MDL system come into existence?

The MDL system was created by an act of Congress in 1968. The law was a response to the filing of more than 1,900 separate civil actions in 36 federal judicial districts involving antitrust allegations against the U.S. electrical equipment industry in the early 1960s. It was the first large-scale complex litigation that swamped the federal judiciary and involved nearly 26,000 claims and 20 product lines.[1]

​

3. Who decides what qualifies as an MDL case?

The United States Judicial Panel on Multidistrict Litigation (JPML), which is composed of a panel of seven district or circuit court judges chosen by the Chief Justice of the United States, determines if a series of pending cases is appropriate to be consolidated into an MDL. If the JPML decides to consolidate, it appoints a federal district court judge to oversee all discovery, pre-trial motions and settlement conferences, and transfers all pending federal cases to that judge. 

  

4. What are the responsibilities of the JPML?​

The panel’s responsibilities include determining whether civil actions involving one or more common questions of fact should be transferred to one federal district court for coordinated or consolidated pretrial proceedings. In addition, the panel selects the judge to conduct the proceedings. The intention of this centralization or transfer process is to avoid duplication of discovery, prevent inconsistent pre-trial rulings and conserve resources of the parties, their counsel and the judiciary. 

​

5. What are the responsibilities of the MDL court?

A single MDL judge oversees and administers cases in an MDL, which includes presiding over pretrial motions, discovery proceedings, and settlement conferences for cases that go forward. The judge might dismiss some claims, or entire cases. In theory, when pre-trial matters are complete, these cases are sent back to the original court where they were first filed, where the trial will take place. In practice this rarely happens. 

​

6. How many MDLs are there?

As of the end of fiscal year 2024, cases consolidated into MDLs constituted 67.8% of the pending federal civil caseload, up from just 29 percent 13 years earlier (excluding most prisoner and social security cases).[2] 

​

As of the end of fiscal year 2024, 481,533 cases were pending in the federal court system. 326,539 of these cases were pending in 1846 MDLs.[3]
​

7. Who has the authority to change the Federal Rules of Civil Procedure?​

The principal policy-making body of the U.S. Courts is the Judicial Conference.

​

Today, the Judicial Conference’s Committee on Rules of Practice and Procedure (“Standing Committee”) and its five advisory committees “carry on a continuous study of the operation and effect” of the federal rules as directed by the Rules Enabling Act.

​

The Advisory Committee on Civil Rules evaluates suggestions (i.e., proposals) for FRCP amendments. If it pursues a proposal, it will seek permission from the Standing Committee to publish a draft of the contemplated amendment for public comment. Based on comments from the bench, bar, and general public, the advisory committee may then choose to discard, revise, or transmit the amendment as contemplated to the Standing Committee.  

​

The Standing Committee reviews the recommendation of the advisory committee and, if satisfied, recommends rule amendments to the Judicial Conference, which in turn recommends the changes to the U.S. Supreme Court. The Court considers the proposals and, if it concurs, officially promulgates the revised rules by notifying Congress before May 1, to take effect December 1 of the same year unless Congress enacts legislation to reject, modify, or defer the pending rules.

​

In 2017, the Advisory Committee on Civil Rules created a subcommittee to examine MDL procedures and third-party litigation funding. In October of 2022, the MDL Subcommittee released a “sketch” of a potential rule 16.1 that would provide clearer guidelines to MDL judges – especially those presiding over MDL cases for the first time – for making effective early management decisions that will facilitate efficient resolution. In June 2023, the first MDL-focused draft Federal Rule of Civil Procedure (FRCP) was published for public comment. In April of 2024, the Advisory Committee unanimously recommended the rule. In June of that year, the Standing Committee voted to approve it, and sent it to the Judicial Conference, which transmitted it to the U.S. Supreme Court. In April of 2025, the U.S. Supreme Court transmitted the rule to Congress. No action was taken by Congress, and Rule 16.1 went into effect on December 1st, 2025.

​

To learn more about the rulemaking process visit Overview for the Bench, Bar and Public.
 

8. What is included in Rule 16.1? 

Rule 16.1 will provide a comprehensive structure for the initial management of MDLs, and one of its key features encourages the parties to exchange information at the outset about the factual basis of claims and defenses to help discourage or reduce meritless cases from infecting the management of MDLs. The rule clarifies that “[t]he Rules of Civil Procedure, including the pleading rules, continue to apply in all MDL proceedings.” It also notes that “the court may find it appropriate to employ expedited methods to resolve claims or defenses not supported after the required information exchange.”

​​

9. Why do Rules4MDLs and LCJ utilize the Duke Law Center methodology for calculating MDLs as a portion of the total civil caseload?

We use the methodology first developed at the Duke Law Center because it most accurately reflects the total number of cases in MDLs as a portion of the civil case load – specifically in regard to the time which must typically be invested by Article III Judges. Cases involving Social Security and prisoner cases (except death penalty cases) are not adjudicated by Article III judges. So, although these cases are part of the civil docket, they are not relevant to the calculation of judges’ workload.

​

Notably, even the raw data demonstrate that the percentage of MDLs as a part of the overall docket has increased dramatically over many years.
 

​

​

[1] Peterson, Jr., Colvin A.; McDermott, John T. (August 1970). "Multidistrict Litigation: New Forms of Judicial Administration". ABA Journal. Chicago: American Bar Association. 56: 737–746.

[2] Based on Duke Law Center methodology. Civil cases include all cases minus social security and prisoner cases, except death penalty cases. Data sources include the JPML’s FY21 ‘Statistical Analysis of Multidistrict Litigation’ report and the United States Courts FY21 ‘Table C-3A’ report.

[3] Ibid.

​​​