Koh said the three plaintiffs, who were accused in 2017 of shoplifting from Walmarts in Florida, Georgia and Texas, did not show that the retailers had specific knowledge of a conspiracy.
She said it did not matter that the retailers might use Corrective Education's database to conduct background checks before deciding to offer the six-to-eight-hour online classes, a portion of whose costs the plaintiffs said was reimbursed to retailers.
"The only alleged commonality each of the defendants have with one another is CEC, whom plaintiffs have chosen not to sue," Koh wrote. "That is not enough to allege one single nationwide conspiracy."
Koh also said she lacked jurisdiction over most defendants in the proposed class action because they did not have enough ties to California, and said the plaintiffs lacked standing to sue retailers that did not harm them.
She gave the plaintiffs 30 days to amend their claims against Walmart, Corrective Education's founders and some of its employees and directors.
Claims against Bloomingdale's, Burlington Coat Factory, Kroger, 99 Cents Only, Save Mart, and Sportsman's Warehouse were dismissed with prejudice, meaning they cannot be brought again.
The plaintiffs were identified as Jane Doe, Mary Moe and John Roe. Their lawyers did not immediately respond on Saturday to requests for comment. Walmart and its lawyers did not immediately respond to similar requests.
Scott Gant, a partner at Boies Schiller & Flexner representing the Corrective Education defendants, said he was pleased with Koh's thoughtful opinion.
Walmart suspended its use of Corrective Education's classes in December 2017, the Wall Street Journal said that month.
The case is Doe et al v Walmart Inc et al, U.S. District Court, Northern District of California, No. 18-02125.