A federal judge ruled a proposed class action accusing Walgreens of overcharging for generic drugs must go forward.

In the lawsuit, filed last June, five customers and an electrical workers’ union’s pension fund accused the company of running a secret dual-pricing scheme that charged customers who bought generics with cash less than the price reported to private and public insurers. Walgreens moved to dismiss the case, claiming the plaintiffs failed to show any false statements of material fact on the company’s part.

Judge John Z. Lee of the Northern District of Illinois disagreed, writing that the higher prices Walgreens reported to insurers constituted false factual statements. Lee also ruled against the motion to dismiss claims against the company under several states’ consumer laws.