MDL 3163 at a Glance
Full Name: In re GLP-1 NAION Products Liability Litigation
Presiding Judge: Hon. Karen Marston
Leadership Appointed: March 3, 2026
Injury Alleged: NAION (optic nerve vision loss)
What is an MDL?
A Multidistrict Litigation (MDL) is a special federal procedure used to consolidate similar lawsuits from across the country before a single judge for coordinated pretrial proceedings. MDLs are used when:
- Many plaintiffs have filed similar lawsuits in different federal courts
- Consolidation will produce efficiencies in discovery and pretrial motions
- The cases involve common factual questions (here: whether GLP-1 drugs cause NAION)
MDLs are not class actions. Each plaintiff retains their own case and their own potential compensation. The MDL process coordinates common pre-trial activities — discovery, expert testimony, dispositive motions — so those aren't repeated thousands of times. Individual cases can be returned to their home districts for trial, or settled globally.
MDL 3163 Timeline
Harvard Study Published
Researchers at Mass Eye and Ear (Harvard Medical School) publish study in JAMA Ophthalmology finding semaglutide users have 4x elevated NAION risk (diabetes patients) and 7.64x elevated risk (obesity patients). Calls for label updates.
First Lawsuits Filed
Individual plaintiffs begin filing product liability lawsuits against Novo Nordisk and Eli Lilly alleging failure to warn of NAION risk. Cases filed in multiple federal districts.
JPML Petition Filed
Plaintiffs' attorneys petition the U.S. Judicial Panel on Multidistrict Litigation (JPML) to consolidate GLP-1 NAION cases into a single MDL for coordinated pretrial proceedings.
JPML Orders MDL Formation
The JPML grants consolidation and creates MDL 3163, assigning the litigation to the Eastern District of Pennsylvania. Judge Karen Marston is assigned as the presiding judge.
Plaintiffs' Leadership Appointed
Judge Marston appoints the Plaintiffs' Steering Committee (PSC) and Plaintiffs' Leadership Structure. This is the formal beginning of coordinated MDL litigation. Initial case management orders expected to follow.
Discovery Phase Begins
Plaintiff Fact Sheets (PFS) issued, defendants serve Defense Fact Sheets, medical record collection begins, depositions of company representatives commence.
Expert Discovery & Daubert Motions
Expert witnesses on causation, damages, and medical issues are disclosed and deposed. Defendants expected to challenge plaintiffs' NAION causation experts via Daubert motions.
Bellwether Trial Selection
A pool of representative cases selected for bellwether trials. These test cases help both sides evaluate case values and litigation risk, typically preceding global settlement discussions.
Trials or Global Settlement
Bellwether verdicts or favorable pretrial rulings typically trigger global settlement negotiations. Resolution timelines for pharmaceutical MDLs vary widely (2–8 years from MDL formation).
Key Defendants
Novo Nordisk
Novo Nordisk is the Danish pharmaceutical giant that manufactures:
- Ozempic (semaglutide injection 0.5mg, 1mg, 2mg) — approved for type 2 diabetes
- Wegovy (semaglutide injection 2.4mg) — approved for chronic weight management
- Rybelsus (oral semaglutide 3mg, 7mg, 14mg) — approved for type 2 diabetes
Ozempic alone had global sales of approximately $14 billion in 2023, with tens of millions of prescriptions filled in the US. Critically, Novo Nordisk has not updated US drug labels to include NAION as a potential adverse event, even after the Harvard study's publication and prescriber alerts issued in other countries.
Eli Lilly
Eli Lilly manufactures:
- Mounjaro (tirzepatide injection) — approved for type 2 diabetes
- Zepbound (tirzepatide injection) — approved for chronic weight management
- Trulicity (dulaglutide injection) — approved for type 2 diabetes
Core Legal Theory
The central allegation in MDL 3163 is failure to warn. Plaintiffs argue that:
- The Harvard study and subsequent research provided defendants with knowledge of the NAION risk
- Defendants had a duty under FDA regulations to update their labels when safety signals emerged
- Novo Nordisk failed to update its US labels despite updating labels in other jurisdictions
- Had adequate warnings been provided, physicians and patients could have made different prescribing decisions
- Plaintiffs suffered NAION — a serious, often permanent injury — as a direct result
Why File Now?
MDL 3163 is weeks old. This is an extraordinarily early stage for a major pharmaceutical MDL. Filing early matters because:
- You ensure your claim is within the statute of limitations
- Your case will be among the first considered for bellwether trial selection
- Early filers often receive more favorable treatment in settlement compensation grids
- Documentation is easier to obtain now while memories are fresh and records intact