Multidistrict litigation (MDL) is a federal legal procedure that temporarily consolidates similar civil lawsuits filed across the United States into a single court for pretrial proceedings. Its primary goals are to save time, reduce costs, prevent inconsistent rulings, and avoid duplicated discovery efforts. Today, MDLs account for roughly 70% of the federal civil caseload. 

Keep reading to learn the differences between multidistrict litigation and class actions, how cases qualify for consolidation, the typical lifecycle of an MDL, and what it all means for teams managing complex ediscovery at scale.

Difference between multidistrict litigation and class action lawsuits

People frequently confuse multidistrict litigation with class action lawsuits because both involve large groups of plaintiffs taking legal action against a common defendant, often large corporations. Despite the surface-level similarity, there are fundamental differences in how these cases are filed, managed, and ultimately resolved in the court system.

How cases qualify for MDL consolidation

For cases to be consolidated under MDL law, they must meet specific statutory requirements under 28 U.S.C. § 1407. These criteria prove that grouping the cases together will benefit both the judicial system and the parties involved. The core requirements include:

• Common questions of fact across the filed cases
• Convenience of the parties and witnesses involved
• Whether consolidation will promote efficient case management

What is the Judicial Panel on Multidistrict Litigation?

The Judicial Panel on Multidistrict Litigation (JPML) is a specialized body consisting of seven federal judges appointed by the Chief Justice of the United States. To ensure a diversity of perspectives, no two judges on the panel can be from the same judicial circuit.

The JPML holds the exclusive authority to determine whether civil actions pending in different federal districts share enough common factual questions to warrant transfer to a single district for coordinated pretrial proceedings. 

The panel meets regularly to hear motions for consolidation. If they decide to centralize a group of cases, the JPML is also responsible for selecting the specific transferee judge and the federal court that will preside over the MDL litigation.

What types of cases are typically consolidated into MDLs?

Certain types of complex litigation naturally lend themselves to multidistrict litigation consolidation because they inevitably produce massive volumes of evidence, involve nationwide impact, and center on shared factual disputes. Common examples include:

• Product liability: These cases typically involve defective products like faulty medical devices, dangerous pharmaceuticals, or flawed automotive parts. The defects can cause identical or similar injuries to thousands of consumers across the country.
• Mass torts: These cases arise when numerous individuals suffer harm from a single catastrophic event or a widespread hazard. Think airplane crash, train derailment, or pervasive industrial accidents that impact a community.
• Securities fraud: Investors file these suits when a publicly traded company allegedly misrepresents its financial health or engages in deceptive practices. Individual claims may be consolidated when they all derive from the same corporate communications.
• Antitrust: Price-fixing schemes, monopolies, and unfair business practices often trigger antitrust MDLs. In these matters, multiple buyers claim economic injury stemming from the same corporate conduct and internal pricing strategies.
• Environmental contamination: When a toxic chemical spill or groundwater contamination affects a large geographic area, affected property owners and residents often file separate claims that are consolidated to streamline the highly technical scientific discovery process.

How the MDL process moves from filing to resolution

Once the JPML consolidates a group of cases, the MDL enters a highly structured pretrial phase. This process is designed to streamline discovery and prevent duplicate work before cases are either settled or sent back for trial.

Court assignment and steering committees

After the JPML assigns the case to a federal judge, that judge typically appoints steering committees for both the plaintiffs and the defendants. These committees are composed of lead attorneys who speak on behalf of the larger group. 

Because an MDL can involve hundreds of individual lawyers, the steering committees are essential for maintaining order. Instead of every lawyer filing redundant motions or conducting duplicate depositions of the same witnesses, the steering committees manage the overarching strategy, coordinate discovery efforts, and handle the day-to-day administration of the litigation on behalf of all involved teams.

Master Complaints and Fact Sheets

To organize thousands of individual claims effectively, the presiding court may require a Master Complaint, which outlines the common allegations shared by all plaintiffs. In response, plaintiffs submit standardized Plaintiff Fact Sheets rather than answering individualized interrogatories. 

These fact sheets capture essential data such as medical history, proof of product usage, and specific injury details in a uniform format. This streamlined approach allows teams to quickly assess the validity, severity, and value of different claims, making it much easier to categorize cases and eventually select representative trials.

Daubert hearings

Multidistrict litigation often revolves around complex scientific, medical, or technical evidence, so expert testimony is critical to both sides. During Daubert hearings, the presiding judge evaluates the methodology and reliability of the expert witnesses proposed by the parties. The judge acts as a gatekeeper, ensuring only scientifically valid testimony reaches a jury. 

If a judge excludes a key expert's testimony for lacking rigorous scientific grounding, it can severely weaken the claims or defenses of an entire group of cases. As a result, these hearings are often pivotal turning points that drive parties toward settlement negotiations.

Bellwether trials

Once general discovery concludes, the court selects a handful of representative cases to go to trial. These initial trials, known as bellwether trials, serve as test cases, allowing both sides to see how juries respond to the evidence, expert testimonies, and legal arguments. 

While the verdicts in bellwether trials only impact the test cases’ plaintiffs, the results provide invaluable real-world data points. These verdicts help teams accurately gauge the risk and potential settlement value of the thousands of cases pending in the MDL.

Settlement or remand

If the bellwether trials result in heavy financial losses for the defendants, it becomes far more likely they will offer a global settlement to avoid the risk and expense of thousands of individual jury verdicts. 

The financial stakes of these agreements can be staggering. In 2025 alone, 33 MDLs officially closed, with at least 18 of them resulting in settlements amounting to $8.5 billion collectively. To distribute these massive sums, steering committees negotiate a settlement framework, often using a matrix or grid system to compensate the remaining plaintiffs based on the severity of their injuries. 

However, if a global settlement cannot be reached, the coordinated pretrial proceedings come to an end. The presiding judge will then remand the unresolved cases back to their original home districts, where they will proceed to individual trials.

Document review challenges unique to MDL cases

The scale of MDL litigation creates unprecedented logistical hurdles, particularly during the discovery phase. Managing electronically stored information (ESI) across massive, consolidated matters requires specialized approaches to ensure accuracy, speed, and cost control.

Keeping review decisions consistent across dozens of teams

In an MDL, multiple law firms often collaborate on the same side of the litigation. With dozens of attorneys across different organizations reviewing a shared corpus of documents, consistency becomes a massive challenge. 

Without strong quality control protocols and unified technology platforms, one reviewer might tag an email as privileged, while a reviewer at a different firm marks it as responsive and non-privileged. This duplicate re-review effort and the resulting inconsistent calls can be disastrous, leading to inadvertent disclosures, strained relationships among co-counsel, or stalled settlement negotiations.

Managing document volume

The largest MDL in history, the 3M Combat Arms Earplug litigation, involved roughly 300,000 individual cases before it was resolved. More recently, Johnson & Johnson proposed a $5.5 billion settlement in July 2026 to resolve roughly 76,000 ovarian talc claims consolidated in federal Multidistrict Litigation (MDL 2738) in New Jersey.

Even after consolidating lawsuits into an MDL, there can be millions — and sometimes billions — of pages of ESI. Teams must collect, process, index, and host sprawling datasets from dozens of corporate custodians, third parties, and plaintiffs. 

This overwhelming volume requires intense, strategic proportionality negotiations under the Federal Rules of Civil Procedure. It also necessitates powerful ediscovery infrastructure capable of ingesting and hosting massive data loads without crashing, lagging, or slowing the review process for the hundreds of concurrent users logged into the system.

Adjusting review as case strategy develops

Multidistrict litigation can drag on for years in the pretrial phase. According to Verisk, data breach and consumer privacy MDLs can resolve in about three years, with complex products liability MDLs remaining pending for more than eight years on average. 

Over that extended timeline, new evidence naturally emerges, judicial rulings alter the scope of the case, and overall litigation theories shift. A document deemed irrelevant during year one might become the smoking gun by year six. 

In a highly dynamic environment like this, teams may need to recode previously reviewed documents to keep the entire document corpus consistent. To survive these shifts, teams need agile review workflows and advanced search capabilities to rapidly locate and re-tag historical data as their strategy evolves.

Protecting privileged and sensitive information at scale

Aggregating data across massive corporate entities, pharmaceutical companies, or healthcare systems exponentially increases the complexity of privilege logs. Furthermore, in health-related MDLs involving medical devices or dangerous drugs, teams must strictly comply with privacy regulations regarding protected health information (PHI). 

Identifying, redacting, and logging every instance of PHI or attorney-client privilege across millions of documents is a monumental and high-risk task. One slip-up could result in judicial sanctions or compromised legal strategies, making automated redaction tools and rigorous privilege workflows essential for success.

Scaling review capacity beyond manual effort

At MDL scale, traditional review approaches can’t keep pace with compressed court deadlines and exploding data volumes. Teams must leverage technology-assisted review (TAR) and artificial intelligence to prioritize important documents and quickly cull irrelevant data from the pile. 

However, both sides — and the presiding judge — must agree on the technological protocols used. This requires employing reliable, verifiable training methods and transparent recall standards that courts trust. It’s vital that the AI-driven review process is accurate and legally sound without requiring manual brute force.

How DISCO supports ediscovery in multidistrict litigation

The demands of MDL litigation — and the sheer scope of document review, coordination, and data processing — can be overwhelming. To maintain strict consistency across geographically dispersed teams while processing millions of complex records, MDLs demand a technological infrastructure built expressly for speed and scale.

DISCO is an all-in-one litigation solution designed specifically for coordinated multi-party document review. With advanced AI capabilities, automated workflows, and lightning-fast search functionality, teams can quickly uncover critical insights while confidently managing massive ESI volumes.

Our dedicated ediscovery software for plaintiff law firms manages complex mass torts and class action work at scale.