A federal appeals court panel on Tuesday expressed skepticism toward the arguments by venerable Bay Area dispensary Harborside that the U.S. Internal Revenue Service is unfairly squeezing cannabis sellers through tax laws.

At issue in the case at the U.S. Court of Appeals for the Ninth Circuit is Section 280E of the Internal Revenue Code, which bars state-legal cannabis companies from deducting traditional business expenses from gross income when they calculate their taxes. The resulting tax bill can erode many operators' profits.