The en banc U.S. Court of Appeals for the Ninth Circuit grilled Shopify on Thursday over its argument that a privacy class action against the Canadian e-commerce company was wrongly filed in California federal court.

The complaint was brought by Brandon Briskin, who ordered apparel from a third-party retailer while in California using payment processing operated by Shopify. Briskin alleges Shopify violated California privacy laws by transmitting software onto his phone to track and create a consumer profile based on his internet activity and sell that data to merchants.