Now, as a new public-health crisis ravages states, Ohio’s Attorney General Mike DeWine filed a lawsuit Wednesday against a handful of pharmaceutical companies, including Purdue Pharma, Teva Pharmaceuticals, and Johnson & Johnson. The lawsuit accuses the companies of spending millions on marketing campaigns that “trivialize the risks of opioids while overstating the benefits of using them for chronic pain.” The companies, the lawsuit alleges, lobbied doctors to influence their opinions about the safety of opioids, “borrowing a page from Big Tobacco.”

The lawsuit follows similar recent lawsuits in Illinois, Mississippi, four counties in New York, and Santa Clara and Orange Counties in California. Last month, the Cherokee Nation filed a lawsuit against distributors and pharmacies in tribal court over the opioid epidemic. In January, the city of Everett, Washington, filed a lawsuit against Purdue Pharma, the makers of OxyContin, alleging that the company knew the drug was being funneled into the black market but did nothing to stop it.

“What you’re getting now is a lot more legal minds across the country focusing on this, and figuring out how to pay these huge bills,” Sam Quinones, the author of Dreamland: The True Tale of America’s Opiate Epidemic, told me. “Everyone is groping for a legal theory that will work in court.”

There is some significant evidence that pharmaceutical companies may have engaged in some activities that led to the opioid crisis. A Los Angeles Times investigation into Purdue Pharma, for instance, found that the drug maker, which marketed OxyContin as relieving pain for 12 hours, knew that the drug wore off before that time period. Since the drug didn’t last as long as promised, some patients suffered withdrawal, which led them to become addicted. (Purdue responded that OxyContin had been approved by the FDA as a 12-hour drug, and said it was working to “address our nation’s opioid epidemic.”)

But the situation differs in significant ways from the tobacco example, and proving the pharmaceutical companies are responsible will be difficult. Individual plaintiffs who have sued pharmaceutical companies over how opioids have been marketed have rarely been successful, according to Richard Ausness, a professor at the University of Kentucky College of Law. Courts have made clear that they believe that individual victims are largely responsible for their addiction. People who die of overdoses are often using the pills not as they were prescribed, but are obtaining the pills on the black market. They are disregarding doctors’ prescriptions and taking more than is safe. “It is difficult to persuade courts that FDA-approved prescription drugs are defective and that their warnings are inadequate,” Ausness told me.

With the tobacco-industry lawsuits, customers were using the product as instructed and got sick. With opioids it’s a different story: Customers are not using the pills as directed, and so it is harder to blame the pharmaceutical companies for the effects of that misuse, according to Lars Noah, a professor of law at the University of Florida. In addition, doctors, not consumers, were the ones targeted by the aggressive marketing campaigns undertaken by pharmaceutical companies, so it can be difficult to link consumer deaths with aggressive marketing.