Four large pharmacy chains are set to face their first trial over the deadly U.S. opioid epidemic, creating new pressure to reach settlements with state and local governments who accuse them of contributing to the public health crisis.

The Ohio counties of Lake and Trumbull allege that oversight failures at pharmacies run by Walgreens Boots Alliance Inc, CVS Health Corp, Walmart Inc and Giant Eagle Inc led to excessive amounts of opioid pills in their communities.

Lawyers for the counties and companies are set to deliver opening statements on Monday to a federal jury in Cleveland, where thousands of similar lawsuits against pharmaceutical companies, drug distributors and pharmacies are pending.

More than 3,300 cases have been brought largely by state and local governments seeking to hold the companies responsible for an opioid abuse epidemic that U.S. government data shows led to nearly 500,000 overdose deaths from 1999 to 2019.