Judge authorizes early causation and preemption motions in GLP-1 vision-loss MDL

A case management order issued July 2, 2026 opened the first substantive motion practice in the federal litigation over NAION vision loss, authorizing early arguments on two questions that will shape the cases: general causation and federal preemption ^[1].

The order, Case Management Order 12, governs MDL 3163, the consolidation of NAION claims in the Eastern District of Pennsylvania before Judge Karen S. Marston ^[1]. The MDL was created December 15, 2025, on Eli Lilly's motion over plaintiffs' opposition, and has grown from about 20 cases at creation to 200 by August 2026, according to the Judicial Panel on Multidistrict Litigation's monthly count as of August 1, 2026 ^[1]. CMO 12 authorizes "early cross-cutting motion practice on general causation and preemption" ^[1].

General causation is the question of whether a drug can cause an injury in the population at large, as opposed to whether it caused a particular patient's injury. Preemption is the argument that federal regulation of drug labels bars state-law warning claims. Both are legal questions decided by the judge, not by a jury, and neither has been ruled on in MDL 3163: the tracker following the docket reports no dismissals, no expert-evidence rulings and no bellwether trial schedule ^[1].

The same two issues are already being fought in the larger stomach-injury MDL, MDL 3094, also before Judge Marston. That track had 3,928 pending cases as of August 1, 2026 ^[1]. Both sides there filed motions to exclude the other side's experts on causation, warning adequacy and preemption, with briefing completed in early August 2026, and a Rule 702 hearing on general causation is set for September 14–18, 2026 ^[1].

Labeling has diverged between regulators. European authorities added NAION to the label as a "very rare" side effect in June 2025, and Australia followed in July 2026, while the U.S. label was unchanged as of August 7, 2026 ^[1].

Recent filings in the home court name Novo Nordisk's semaglutide products (Ozempic, Wegovy, Rybelsus) and Eli Lilly's Mounjaro and Zepbound (tirzepatide) and Trulicity, according to the tracker's review of public dockets ^[1].

Why it matters for patients

These are procedural steps, not findings. No court or jury has found that any GLP-1 medication caused anyone's injury, and no case in either MDL has been settled, according to the tracker ^[1]. Nothing in CMO 12 changes what is known about the drugs' risks or how they are prescribed, and the order does not address dosing or treatment.

What the order does is set the order in which the vision-loss cases will be tested. If a court accepts the preemption argument, state-law warning claims could be dismissed before any evidence is heard; if it accepts the causation arguments, claims could narrow. Either outcome would apply across the MDL rather than case by case.

Patients who believe they were injured face the same practical reality as before: whether an individual has a claim depends on that person's medical records and the law of their state, the tracker states ^[1]. NAION is described in the litigation materials as sudden vision loss in one eye, and the tracker notes that not everyone who reports it has permanent loss ^[1].

What happens next

The next dated milestone is the September 14–18, 2026 Rule 702 hearing in MDL 3094, which will decide which expert testimony that litigation proceeds with ^[1]. The tracker lists as open items the first substantive motions under CMO 12 in MDL 3163, any U.S. Food and Drug Administration action on NAION labeling, monthly JPML case counts, and any first bellwether scheduling in either MDL ^[1]. No dates have been reported for the CMO 12 motions or for a ruling on them. Separately, the New Jersey Supreme Court designated two GLP-1 multicounty litigations, one per injury track, in Bergen County before Judge Gregg A. Padovano on October 16, 2025 ^[1].