A federal jury in Cleveland on Tuesday found that the companies owning CVS, Walgreens and Walmart pharmacies were liable for contributing to the opioid epidemic in two Ohio counties—the first, potentially influential verdict among many lawsuits targeting pharmacy chains.

In the suit, attorneys for Lake and Trumbull counties in northeastern Ohio had argued that the chains failed to stop pain pills from flooding the counties and false prescriptions from being filled. The counties argued that by enabling the opioid crisis the pharmacy companies had created a public nuisance costing them each about $1 billion in law-enforcement, social-services and court expenses.