PROVIDENCE, R.I. (WPRI) -- The U.S. Department of Justice has filed a lawsuit against Woonsocket-based CVS Health, accusing the pharmaceutical giant of filling prescriptions for controlled substances that "lacked a legitimate medical purpose," according to U.S. Attorney Zachary Cunha.

The civil complaint, unsealed Wednesday, states CVS violated the Controlled Substances Act by knowingly filling prescriptions for controlled substances that were not valid or not issued in the usual course of medical practice.

The prescriptions that CVS, which is the country's largest pharmacy chain, unlawfully filled date back to Oct. 17, 2013, and run through present day, according to the complaint.

Of note, the complaint accuses CVS of filling "dangerous and excessive quantities of opioids, early fills of opioids, and 'trinity' prescriptions, an especially dangerous and abused combination of drugs made up of an opioid, a benzodiazepine and a muscle relaxant."

Cunha said CVS also allegedly filled excessive quantities of prescriptions for controlled substances written by prescribers that it knew were engaged in "pill mill practices."

The complaint alleges that CVS ignored substantial evidence -- including from its own pharmacists and internal data -- that indicated its stores were dispensing unlawful prescriptions.

In the complaint, the DOJ blames CVS's violations on "corporate-mandated performance metrics, incentive compensation and staffing policies that prioritized corporate profits over patient safety."

Specifically, the complaint accuses CVS of short-staffing its pharmacies to a point where its pharmacists can't properly vet each prescription. CVS also reportedly deprived its pharmacists of crucial information that could've refused the number of unlawful prescriptions filled, such as by preventing them from warning each other about certain prescribers.

Cunha said CVS's actions "helped fuel the prescription opioid crisis and that, in some particularly tragic instances, patients died after overdosing on opioids shortly after filling unlawful prescriptions."

"Opioid deaths remain a scourge on communities across Rhode Island and the nation, robbing families of loved ones and leaving a path of devastation in their wake," Cunha said. "This lawsuit alleges that CVS failed to exercise its critical role as a gatekeeper of dangerous prescription opioids and, instead, facilitated the illegal distribution of these highly addictive drugs, including by pill mill prescribers."

"When corporations such as CVS prize profits over patient safety and overburden their pharmacy staff so that they cannot carry out the basic responsibility of ensuring that the prescriptions are legitimate, we will use every tool at our disposal to see that they answer for it," he continued.

CVS is also accused of violating the False Claims Act by seeking reimbursement from federal health care programs for some of the unlawfully filled prescriptions.

If CVS is found liable, Cunha said it could face civil penalties for each unlawfully filled prescription, plus treble damages and applicable penalties for each one that was illegally reimbursed.

In a statement, a spokesperson for CVS said the company strongly disagrees with the allegations and "false narrative" in the complaint, adding that they've been cooperating with the DOJ's investigation for more than four years.

"We will defend ourselves vigorously against this misguided federal lawsuit, which follows on the heels of years of litigation over these issues by state and local governments -- claims that already have been largely resolved by a global agreement with the participating state Attorneys General," the statement said.

CVS claims the lawsuit seeks to "impose a shifting standard for pharmacy practice," saying the government has previously failed to provide proper guidance on the matter.

"Each of the prescriptions in question was for an FDA-approved opioid medication prescribed by a practitioner who the government itself licensed, authorized, and empowered to write controlled-substance prescriptions," the statement continued.

The spokesperson also pointed out that CVS has a program to "block controlled-substance prescriptions written by doctors of potential concern," which has resulted in lawsuits claiming the company went to far in some instances.