Walmart sues US government, claiming opioid rules are unclear

America’s biggest retail chain, Walmart, which operates more than 5000 pharmacies in its stores, is suing the US Department of Justice and Drug Enforcement Agency to pre-empt an anticipated government lawsuit or prosecution over its filling of opioid prescriptions.

Walmart is one of several pharmacy and drug distribution companies that have drawn official criticism or been sued by state or federal governments for allegedly ignoring suspicious prescribing patterns that they had a duty to report, such as doctors whose patients were all taking painkillers, or stores whose opioid sales could not be feasibly explained by the medical needs of the …