Courthouse News reports that federal judge cleared the way last week for San Francisco’s opioid lawsuit against Walgreens and a number of pharmaceutical companies to head to trial, which is set to begin on April 25.

Thousands of states, cities and counties have sued pharmaceutical companies over their role in the opioid epidemic, which is believed to have been caused by the marketing and overprescription of prescription drugs like Oxycontin. Many patients who were prescribed an opiate later switched over to using illegal narcotics like heroin. According to the CDC, nearly half a million people died from opiate overdoses between 1999 and 2019.

The biggest culprit was Purdue Pharma, which manufactured and marketed Oxycontin, and which entered bankruptcy in 2020. That proceeding hit the pause button on all lawsuits against Purdue, and eventually lead to a massive settlement, in which cities and states will effectively take over ownership of Purdue. The former owners of the company, the Sackler family, contributed $6 billion to the settlement, a good deal of which went to the governmental entities, in exchange for immunity from future lawsuits.

The drugmaker Johnson & Johnson and three pharmaceutical distributors agreed to a $26 billion settlement with states and municipalities in February.

But that still leaves a multitude of other opioid-related lawsuits in active litigation.

San Francisco filed its suit in 2018 against a panoply of defendants, including Purdue, nine members of the Sackler family and a host of other companies. Some of those defendants, like Purdue, have been released from the case thanks to settlements. But some parties remain, including Walgreens, Actavis, Teva Pharmaceuticals and Endo Pharmaceuticals, the latter two of which specialize in making generic versions of drugs.

The city’s suit made a number of what were at the time novel allegations, including public nuisance and racketeering. In 2020, U.S. District Judge Charles Breyer dismissed the racketeering claims, but allowed the public nuisance claims to go through.

Last week, Judge Breyer further whittled down the list of defendants. In a 9-page decision, Breyer dismissed claims against parent company Endo International, writing, “evidence fails to suggest that Endo subsidiaries are ‘merely an instrumentality’ of Endo International.” He also dismissed claims against a subsidiary, Par Pharmaceuticals. But Endo Pharmaceutical and Endo Health Solutions must still stand trial.

San Francisco has made two claims about the company – that it “made false and misleading statements about the safety and risks of opioids,” and that it “failed to design and operate effective systems to identify suspicious orders of opioids and to prevent diversion of opioids.” Both of those failures, the city claims, amounted to a public nuisance.

In another, much shorter decision, Breyer dismissed motions for summary judgment from five other defendants, including Teva and Walmart.

The strategy of suing opioid companies by alleging public nuisance has had a mixed track record. An Orange County Superior Court Judge, in November 2021, ruled in favor of four pharmaceuticals (including Endo and Teva) after a bench trial in a lawsuit brought by the counties Santa Clara, Los Angeles and Orange and the city of Oakland. That same month, an Oklahoma Supreme Court overturned a $465 Million ruling against Johnson & Johnson, rejecting the public nuisance argument.

Other lawsuits against drugmakers alleging public nuisance are still pending, including a trial in West Virginia, which started this week.