MDL wave poised to reshape 2026 casualty landscape

Multidistrict litigation (MDL) has quietly become one of the most consequential forces in the US casualty sector. Once a procedural tool known mainly to trial lawyers, MDL now dominates federal civil dockets and increasingly drives long-tail losses, defense costs and pricing pressure across general liability lines.

The 2026 trial calendar is being reshaped by a series of postponed bellwether trials in some of the biggest mass-tort proceedings, with growing implications for insurers, reinsurers, brokers and insureds alike.

At its most basic level, MDL allows lawsuits with common factual questions to be centralized before a single federal judge for coordinated discovery and pretrial proceedings. That can mean claims tied to a mass disaster, such as an oil spill, or allegations linked to the same product or chemical exposure filed in courts across the country.

“Multidistrict litigation has played a large role in liability catastrophes,” said Katherine Lynch, a data analyst on Verisk’s Emerging Issues team, in a recent webinar.

Why the insurance industry should be watching MDLs in 2026

MDLs often rely on bellwether trials, in which a limited number of representative cases are tried first. The outcomes can shape settlement discussions and legal strategies for thousands of related claims that were never heard in court.

For insurers, those early trials can provide important, and sometimes costly, signals about eventual exposure.

Some MDLs have reached historic scale. The 3M Combat Arms Earplug products liability litigation, now resolved, is the largest MDL ever created. At its peak, it included as many as 260,000 cases and ultimately resulted in a $6-billion settlement.

Other high-profile examples include the Roundup herbicide litigation, which produced major settlements but still has thousands of cases pending, and a $19-million settlement reached in September 2024 over a defective infant sleeper.

Settlements are a frequent outcome. Verisk data show that over the past two years, 48 MDLs closed, with 22 ending in settlement. Those included common-disaster cases, medical device litigation, and data breach and consumer privacy matters. While many settlements are negotiated through plaintiffs’ steering committees, Lynch said the volume and consistency of outcomes underscore the importance of monitoring MDLs closely.

For insurers, the risks extend beyond settlement. MDLs tend to last for years, compounding defense costs over long periods. The average creation year for active MDLs in Verisk’s database is 2019.

According to Verisk, product liability continues to drive many of these trends. Cosmetic, pharmaceutical and medical device MDLs remain among the most active categories, alongside long-running litigation over firefighting foam and environmental contamination.

At the same time, Verisk said data breach and consumer privacy MDLs are becoming more common as cyber incidents proliferate, though individual dockets remain relatively small for now.

Here are some MDLs Verisk cited as key cases to watch: