Internal documents cited during the opening session of a landmark opioid trial in Cleveland suggest the nation's biggest pharmacy chains were warned by employees about the dispensing of highly addictive pain pills.

Mark Lanier, lead attorney for two Ohio counties suing CVS, Giant Eagle, Walgreens and Walmart, read the documents into the court record as part of his opening statement.

"Walgreens is not verifying the legitimacy of suspicious orders, which could lead to the fulfilment of an illicit order," said one Walgreens memo cited by Lanier.

A separate communication from a CVS employee warned that the company's safeguards, designed to reduce prescription opioid abuse, might be inadequate.

"I may have been naïve to believe we were doing everything we could to reduce the growth of this tragic problem in the U.S.," the CVS document cited by Lanier stated.

NPR asked CVS and Walgreens to comment on the documents. CVS hasn't responded. A spokesperson for Walgreens declined to comment.

This is the latest trial to test the liability of corporate America for an opioid crisis that has killed hundreds of thousands of people.

The companies deny any wrongdoing. But most experts agree that the drug epidemic spiraled out of control in the late 1990s when corporations began manufacturing, distributing and selling far more highly addictive prescription pain pills.

Under the federal Controlled Substances Act, firms involved in the opioid business — including pharmacy chains — are required to implement strict monitoring and safety programs.

Lanier told jurors Monday that chain pharmacies were "the last line of defense ... and they failed at that job."

Companies push back, blaming doctors and regulators

In legal filings and opening statements this week, however, attorneys for the pharmacy chains maintain they made a good-faith effort to properly control opioid sales.

"Nobody's here to tell you the opioid crisis is unimportant," said Kaspar Stoffelmayr, an attorney for Walgreens.

But, he told jurors, any blame for the addiction epidemic should fall elsewhere: on doctors who wrote a growing number of prescriptions and on government regulators who failed to crack down on pill mills.

"The internet was a huge problem," Stoffelmayr said. "People used to be able to order opioid medications online."

An attorney for CVS sounded a similar note: "Pharmacies don't control volume [of opioids] dispensed," said Eric Delinsky. "Doctors do because they're the ones who write prescriptions."

An attorney representing Walmart also sought to draw a distinction between prescription medications and the devastation in Ohio caused by the wider opioid epidemic.

John Majoras told jurors much of the problem involves "heroin, illegal drugs and things that have nothing to do with Walmart."

Many public health experts, however, believe patients who become addicted to prescription opioids later transition to illicit street drugs.

An Ohio trial that could echo nationwide

The venue for this federal trial is significant. Ohio has been hit particularly hard by the opioid crisis, with one of the highest overdose death rates in the nation.

Evidence and testimony presented over the next two months will focus primarily on the dispensing of millions of pain pills at pharmacies in Lake and Trumbull counties near Cleveland.

But this case is widely seen as a legal test that will determine whether companies will shoulder part of the massive cost of responding to the opioid epidemic nationwide.

More than 3,300 state and local governments have filed similar lawsuits against the pharmacy chains. If the companies lose, total payouts are expected to run into the billions of dollars.

While this trial unfolds, separate opioid trials against other companies involved in the opioid business are underway or awaiting rulings in California, New York and West Virginia.

A $26 billion national opioid settlement involving three drug wholesalers as well as the drugmaker Johnson & Johnson is also in the final stages.

Purdue Pharma, the maker of Oxycontin, has also reached a bankruptcy settlement valued at between $5 billion and $10 billion that now faces a federal appeal.

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