Karl Kahn upgraded to Anthropic's $200-a-month Claude Max 20x plan for intensive coding work. Within one five-hour session, he had burned through 15 percent of his weekly quota. That discrepancy became the seed of a proposed class action, and on Friday, a federal magistrate judge in California found that the complaint has legs.
Magistrate Judge Alex Tse ruled that Anthropic must face claims of negligent misrepresentation and breach of contract over how it advertised its premium Claude subscription tiers. Tse dismissed several other claims but allowed the case to move forward on the central question: whether Anthropic's sales pages misled subscribers about what they were buying.
"The advertising in question is plausibly misleading," Tse wrote in his November 6 order in Kahn v. Anthropic.
The Math That Didn't Add Up
Anthropic sells Claude Pro at roughly $20 a month and two higher tiers: Max 5x at $100 and Max 20x at $200. Those names promised five and twenty times the usage of Pro. The plaintiffs, Kahn and fellow subscriber Solomon Smith, calculated that on Claude Sonnet, the $200 plan delivered about six times Pro's weekly usage. The $100 plan got them roughly 3.5 times.
The gap exists because the advertised multiplier applies to a rolling five-hour session window, not the week. Anthropic added weekly caps in late July 2025, months after Max launched in April of that year. The plaintiffs allege those constraints were never made sufficiently clear.
Anthropic argued customers should understand "more usage" as a per-session promise and pointed to a help page that explained the distinction. Tse rejected that defense at this stage. The per-session disclosure, he wrote, "is located two hyperlinks away from the primary sales pages on claude.com." Purchasers did not need to visit it to complete sign-up.
What Survived and What Didn't
The order is a mixed result. Tse let the negligent misrepresentation and breach-of-contract claims proceed. He found the contracts could include the sales pages because Anthropic's terms point customers to "the order process" for subscription details.
He dismissed claims under two California statutes covering unfair business practices and false advertising. Because Kahn and Smith remained subscribers despite knowing about the disputed marketing, Tse found they had not shown they could seek a court order requiring Anthropic to change its ads. Kahn's claim under the state's Consumers Legal Remedies Act was also dismissed, though Tse gave him a chance to add detail. Smith's consumer-law claim survived.
The plaintiffs also alleged Anthropic acted unfairly by tightening limits mid-billing-period. Tse rejected that too: "Anthropic didn't tighten usage limits as a bait-and-switch," he wrote.
A Quiet Rename
Nine days before the ruling, Anthropic quietly renamed its tiers. Max 5x became Max; Max 20x became Ultra. Prices stayed the same. Verified Ultra accounts lost their five-hour session limit, though weekly caps remain. The lawsuit concerns how the old names were advertised, not the October rebrand.
The case now has a December 2 deadline for the plaintiffs to file an amended complaint. If they do not, Anthropic must answer by December 16. No class has been certified, and no court has ruled that Anthropic misled anyone. Anthropic and the plaintiffs did not respond to Courthouse News's request for comment.
