AFFF MDL parties, claims, and case count in 2026
The AFFF MDL in the U.S. District Court for the District of South Carolina remains one of the largest PFAS proceedings in the federal system. The court’s MDL introduction states that the litigation has had roughly 10,000-plus associated cases involving PFAS and AFFF contamination claims. That scale matters because it shapes everything else in 2026: bellwether selection, expert scheduling, compliance orders, and the pace of motion practice.
The parties include plaintiffs alleging injury or contamination tied to aqueous film-forming foam, along with defendants connected to PFAS and AFFF products. In practical terms, the MDL is handling a large inventory of claims while also trying to build trial-ready records in selected personal-injury cases. That is why the court’s 2026 orders focus so heavily on expert discovery and structured bellwether tracks.
For claimants, the key point is simple: the MDL is no longer just about broad allegations over PFAS and AFFF contamination. It is also about whether specific cases are prepared well enough to move through expert review, Daubert-style challenges under Federal Rule of Evidence 702, and eventual trial settings. In a docket this large, the court is using detailed case-management orders to keep the litigation moving.
Readers who want a broader overview of the litigation can also review our AFFF Lawsuit Update and PFAS Contamination Guide. For ongoing coverage across the site, visit the Firefighting Foam Blog.
2026 bellwether track for thyroid and liver cancer claims
In 2026, one of the most important developments is the court’s decision to set a schedule for thyroid and liver cancer bellwether science work. Case Management Order No. 33C addresses further expert discovery and Rule 702 challenges for thyroid and liver cancer claims. That means the litigation is entering a phase where the court will test whether expert opinions on causation and related issues meet the standards for admissibility.
Bellwether tracks matter because they give the parties and the court a structured way to evaluate recurring issues in a smaller set of cases before broader trial activity. In the AFFF MDL, the thyroid and liver cancer track puts scientific proof at the center of the next stage. The fight is not only over what experts say, but also over whether those opinions are reliable enough to reach a jury under Rule 702.
For plaintiffs, this stage is critical. If expert opinions survive Rule 702 challenges, those rulings can shape settlement pressure and trial strategy across similar cases. For defendants, expert challenges are a direct way to narrow claims, limit testimony, or block certain causation theories before trial. In a mass tort involving PFAS and AFFF, those rulings often carry weight far beyond the individual bellwether cases.
The practical takeaway for firefighters and other claimants is that 2026 is a science-heavy year in the MDL. The court is not pausing the litigation. It is pressing forward with a timetable that forces both sides to put their expert records in order.
Expert-deposition schedule and Rule 702 motion deadlines
Case Management Order No. 33C is the central scheduling order for this part of the 2026 bellwether process. The order set 2026 expert-deposition and Rule 702 motion deadlines for thyroid and liver cancer claims. Those deadlines are important because they mark the transition from written expert reports into live testing of expert opinions through depositions and admissibility briefing.
Expert depositions are where each side probes the foundation for the other side’s opinions. In the AFFF MDL, that means close scrutiny of causation analysis, exposure assumptions, methodology, and the fit between an expert’s conclusions and the facts of the selected cases. Once those depositions are complete, Rule 702 motions give the parties a formal path to ask the court to admit, limit, or exclude expert testimony.
Rule 702 fights are often decisive in personal-injury bellwether cases. If a plaintiff’s causation expert is excluded, the case can become much harder to try. If a defense expert is limited or excluded, the plaintiff’s path to trial can become stronger. That is why the 2026 deadlines in Case Management Order No. 33C deserve close attention from anyone following thyroid and liver cancer claims in the District of South Carolina MDL.
Claimants should also understand what these deadlines do not mean. A scheduling order does not resolve the merits of all thyroid or liver cancer cases. It sets the timetable for the next major contest: whether the expert proof in the selected bellwether cases clears the Rule 702 gatekeeping process.
Group B bellwether selection and ulcerative-colitis case schedule
The court is also moving ahead with Group B personal-injury bellwether work. Case Management Order No. 26N is the scheduling order governing Group B personal injury bellwether trial pool cases. That order matters because it keeps the second wave of bellwether preparation on track while the thyroid and liver cancer expert process unfolds.
One of the clearest 2026 markers in this area is the schedule for an ulcerative-colitis plaintiff. The order advanced Group B bellwether work and set July 20, 2026 proposals for the ulcerative-colitis plaintiff moving into expert discovery. That date gives the parties a concrete checkpoint for how the next selected case will proceed.
Ulcerative-colitis scheduling is significant for two reasons. First, it shows that the MDL is not focused on only one disease category at a time. The court is managing parallel tracks. Second, it shows that the bellwether process is becoming more granular, with individual plaintiffs moving into expert discovery under court-set deadlines rather than broad, open-ended planning.
For claimants, Group B activity is a reminder that the MDL’s trial-preparation work is expanding. If a case is selected for bellwether treatment or placed near that process, deadlines become tighter and the demands of expert discovery become more immediate. In a large MDL, that shift can happen quickly once the court enters a scheduling order.
Plaintiff-compliance enforcement and case-management requirements
Case Management Order No. 37 is a key order for understanding the court’s compliance posture in 2026. Even without turning every docket step into a headline, the direction is clear: the court is enforcing case-management requirements and expects plaintiffs to meet deadlines and procedural obligations. In a litigation with roughly 10,000-plus associated cases, that enforcement is not a side issue. It is part of how the MDL functions.
Plaintiff-compliance enforcement usually centers on whether required materials are submitted on time, whether case-specific information is complete, and whether parties follow the structure laid out in prior orders. In a mass tort, those requirements are the framework that lets the court sort ready cases from stalled ones. When the court tightens enforcement, the immediate effect is pressure on individual claimants and their counsel to cure deficiencies fast or face consequences under the MDL’s management system.
For firefighters and other AFFF claimants, the lesson is practical rather than abstract. A filed case is not enough by itself. The court expects compliance with the orders governing disclosures, scheduling, and case progression. Missing deadlines or failing to provide required information can put a claim at risk of delay or other adverse action.
That is why 2026 stands out as a year of both scientific gatekeeping and procedural discipline. The District of South Carolina is not only deciding how bellwether science disputes will be briefed and argued. It is also making clear that plaintiffs must keep their cases in active compliance with MDL requirements.
What firefighters and other AFFF claimants should watch in upcoming MDL orders
For firefighters, military personnel, airport workers, and other AFFF claimants, the next MDL orders are likely to matter most in four areas.
First, watch the Rule 702 briefing and rulings tied to Case Management Order No. 33C. Those decisions will shape the strength of thyroid and liver cancer bellwether cases and influence how both sides value similar claims.
Second, watch whether the Group B schedule under Case Management Order No. 26N stays on pace, especially around the July 20, 2026 proposals for the ulcerative-colitis plaintiff moving into expert discovery. If that track continues without major disruption, it signals that the court intends to keep multiple disease categories moving at once.
Third, watch compliance orders such as Case Management Order No. 37. In a docket with roughly 10,000-plus associated cases, enforcement orders tell claimants how strictly the court is policing deadlines and case-specific obligations. Those orders can affect who stays on track for meaningful case development and who falls behind.
Fourth, watch the District of South Carolina MDL page itself. The court’s posted orders are the best place to see whether deadlines are extended, whether new bellwether candidates are identified, and whether the court changes the structure of expert discovery or motion practice.
The broad picture for 2026 is straightforward. The AFFF MDL is entering a more demanding phase. The science fights are becoming sharper, the bellwether tracks are becoming more defined, and the court is showing less tolerance for weak compliance. Claimants who keep close track of scheduling orders and meet every case-management requirement will be in a better position than those who treat the MDL as a slow-moving docket with little day-to-day consequence.
Sources
- SCD - MDL Introduction
- Case Management Order No. 33C (Scheduling Further Expert Discovery and Rule 702 Challenges for Thyroid and Liver Cancer)
- Case Management Order No. 26N (Scheduling Order Governing Group B Personal Injury Bellwether Trial Pool Cases)
- Case Management Order No. 37
Last updated
April 17, 2026
