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Frequently Asked Questions


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 pursuant to 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 new 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 who are 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 a number of similar pending cases meet the test to become an MDL, it appoints an MDL judge – a federal district court judge – to oversee all discovery, pre-trial motions and settlement conferences, and transfers all pending federal cases to the same 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 2023, MDL cases constituted 71.3% of the pending federal civil caseload, up from just 29 percent 12 years earlier. (Excluding most prisoner and social security cases.).[2] 

As of the end of fiscal year 2023, 584,986 cases were pending in the federal court system. 417,137 of these cases were pending in 1846 MDLs.[3]

7. What rules govern MDLs? 

According to Rule 1 of the Federal Rules of Civil Procedure (FRCP), the FRCP “govern the procedure of all civil actions and proceedings in the United State district courts.”[4] However, because an MDL case today can have hundreds or even thousands of individual claims, certain aspects of the FRCP are difficult or even impossible to apply.

For example, the FRCP’s discovery rules contemplate requests, motions and protective orders, a system that may be unworkable in an MDL proceeding with 1,000 plaintiffs. Streamlining discovery in MDL cases could be as straightforward as modifying Rule 26, which requires certain discovery disclosures without individualized requests or motions. Such an amendment would adapt the FRCP to the practical needs of MDL cases and provide participants in MDL cases the same clarity, principles and protections that the FRCP provide in all other cases.  

8. What should be changed about how MDLs currently are being handled by the federal judiciary? 

Currently, many judges resort to improvising ad hoc practices because the FRCP no longer provide practical presumptive procedures in MDL cases. Although some individual practices have more merit than others, they all share the same lack of clarity, uniformity and predictability that the FRCP ensure in all other civil cases. Many common MDL practices also cause an unbalanced litigation environment by failing to provide protections inherent in the FRCP.  


9. Would these changes make it more difficult for injured parties to sue a defendant?

No. Clear, uniform rules in MDL cases would bring fairness, clarity and certainty to the system, benefiting all parties and disadvantaging none.  In fact, written procedures would help address the “repeat player” problem in MDL cases, which exists because only a small, exclusive group of people knows how the game is played. FRCP amendments could help lead to greater inclusion by women and minorities by providing rules that are accessible to everyone. 

10. Who has the authority to change the 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 rules committees “carry on a continuous study of the operation and effect” of the federal rules as directed by the Rules Enabling Act.[5]

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 independently reviews the findings of the advisory committee and, if satisfied, recommends changes to the Judicial Conference which in turn recommends changes to the Supreme Court. The Court considers the proposals and, if it concurs, officially promulgates the revised rules by order before May 1, to take effect no earlier than December 1 of the same year unless Congress enacts legislation to reject, modify, or defer the pending rules.


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

11. Has the Advisory Committee on Civil Procedures decided to review proposals for amendments to the Federal Rules of Civil Procedure?

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. The proposed rule is expected to be considered at the next Advisory Committee on Civil Rules meeting in March of 2023. If the proposal is approved, it will be sent to the Standing Committee on Rules of Practice and Procedure and then, if approved by the Standing Committee, will be published for public comment. ​

Mountains of unexamined claims in an MDL proceeding hamper judges’ ability to make good initial management decisions and reduce the possibility of timely resolution. Without considering these important questions early in the litigation, counsel and parties are deprived of the information they need to assess litigation risks and valuation. Allowing unexamined claims to be filed and linger without review conflicts with the clear purpose of the FRCP’s rules requiring plaintiffs’ attorneys to conduct diligence before filing their claims.

12. Can the general public stay updated on what amendments or changes are being considered?

We will update this website as more information about the Committee’s work becomes available and you can join our email list here.

Information regarding the rulemaking process generally is available at​​

13. 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’ work load.

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.

[4] Fed. R. Civ. P. 1. 


​[6] (The National Law Journal, Amanda Bronstad, Nov. 9, 2017.

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