The U.S. Department of Justice has sued Deerfield-based Walgreens, saying the drugstore chain’s pharmacists filled "unlawful" prescriptions for opioids and other controlled substances that helped fuel the country’s prescription painkiller crisis.In a civil lawsuit filed on Thursday in the U.S. District Court in Northern Illinois, the Justice Department also said Walgreens pressured its pharmacists to fill prescriptions without confirming their validity.The company is one of the country’s largest drugstore chains with more than 8,000 locations across the U.S. Related Walgreens closing 5 stores on South and West sides “This lawsuit seeks to hold Walgreens accountable for the many years that it failed to meet its obligations when dispensing dangerous opioids and other drugs,” Brian Boynton, principal deputy assistant attorney general and head of the Justice Department’s civil division, said in a news release on Friday. “Walgreens pharmacists filled millions of controlled substance prescriptions with clear red flags that indicated the prescriptions were highly likely to be unlawful."The company’s practices “allowed millions of opioid pills and other controlled substances to flow illegally out of Walgreens stores,” Boynton said.Walgreens and its subsidiaries sought reimbursement for many of those prescriptions from federal health care programs, according to the complaint. A Walgreens spokesperson said in an emailed statement on Friday: “We are asking the court to clarify the responsibilities of pharmacies and pharmacists and to protect against the government’s attempt to enforce arbitrary 'rules' that do not appear in any law or regulation and never went through any official rulemaking process. We will not stand by and allow the government to put our pharmacists in a no-win situation, trying to comply with ‘rules’ that simply do not exist.”The Justice Department’s lawsuit said pharmacists filled unlawful prescriptions “for the especially dangerous and abused combination of drugs known as the ‘trinity,’ which is made up of an opioid, a benzodiazepine and a muscle relaxant.”Walgreens said it "stands behind our pharmacists, dedicated healthcare professionals who live in the communities they serve, filling legitimate prescriptions for FDA-approved medications written by DEA-licensed prescribers in accordance with all applicable laws and regulations. ... We look forward to the opportunity to defend the professionalism and integrity of our pharmacists.”The lawsuit comes on the heels of the company confirming that it would close five stores in February on the South and West sides. The company said last week that it shuttered 70 locations in its first quarter, as it reported better-than-expected quarterly earnings. In October, Walgreens announced plans to close 1,200 stores by 2027. The Justice Department in December unsealed a similar civil complaint against CVS Pharmacy and its subsidiaries, saying it filled “unlawful” prescriptions for opioids and other drugs then sought reimbursement from federal health care programs, in violation of the False Claims Act. CVS is the largest pharmacy chain in the U.S., with more than 9,000 outlets.The complaint followed an announcement in December that consulting firm McKinsey & Co. agreed to pay $650 million to settle a federal investigation into its work to help opioid manufacturer Purdue Pharma boost the sales of the highly addictive drug OxyContin.In 2022, Walmart agreed to pay $3.1 billion to settle lawsuits nationwide over the impact of prescriptions its pharmacies filled for powerful prescription opioid painkillers.Federal prosecutors seek to hold companies accountable for the U.S. addiction and overdose crisis, with opioids linked to more than 80,000 annual deaths in some recent years. For the past decade, most of the deaths have been attributed to illicit fentanyl, which is laced into many illegal drugs. Earlier in the epidemic, prescription pills were the primary cause of death.Contributing: AP