(Reuters) - A federal judge has dismissed Walmart Inc’s lawsuit seeking to preemptively block the U.S. government from blaming the world’s largest retailer for its alleged role in fueling the nation’s opioid crisis. U.S. District Judge Sean Jordan said the government had not waived its sovereign immunity from Walmart’s “sweeping” challenge to the Department of Justice’s and Drug Enforcement Administration’s enforcement of laws governing opioid prescriptions by pharmacies and pharmacists. Walmart said on Friday it will appeal the decision, which the Plano, Texas-based judge issued on Thursday night. Jordan ruled six weeks after the government filed its own lawsuit against Walmart, claiming its network of more than 5,000 pharmacies was unable to adequately detect and report suspicious opioid prescriptions. It also said Walmart did the opposite, filling thousands of invalid prescriptions. In its Oct. 22 lawsuit, Walmart had said the government’s lax and confusing oversight left pharmacists with an “untenable” choice between filling prescriptions and risking criminal or civil liability, or refusing prescriptions and facing the wrath of patients, doctors and state medical boards. “Our pharmacists and patients deserve better than the current patchwork of inconsistent, conflicting and contradictory demands from federal and state regulators,” the Bentonville, Arkansas-based retailer said in announcing the planned appeal. The Justice Department’s lawsuit against Walmart was a significant escalation of its efforts to hold major pharmacies responsible for their roles in an U.S. opioid epidemic in which about 450,000 people died from overdoses from 1999 to 2018. It is seeking civil damages for Walmart’s alleged violations of the Controlled Substances Act on a “nationwide scale,” both as a pharmacy and as a distributor.