A federal judge in San Francisco declined on Thursday to give final approval to Anthropic's proposed $1.5bn settlement with authors who say the company trained its Claude models on pirated books, asking lawyers for more detail on counsel fees and payments to the three lead plaintiffs before she would sign off.

Judge Araceli Martínez-Olguín, who inherited the case from Judge William Alsup after a reassignment earlier this year, presided over the fairness hearing in Bartz v. Anthropic.

The class is led by thriller novelist Andrea Bartz and nonfiction writers Charles Graeber and Kirk Wallace Johnson, and the deal would resolve a suit alleging Anthropic downloaded more than seven million books from the shadow libraries LibGen and Pirate Library Mirror to train its models.

On the headline arithmetic, the settlement covers roughly 480,000 works and pays out around $3,000 per work after fees, the largest known sum in a US copyright case.

Per a claims report filed in April, claims have been registered for about 91% of the eligible works, an attorney for the class told the court that the number was now above 92% as of Thursday.

What the judge wanted to talk about was the slice that does not go to authors. Class counsel had already trimmed its fee request from 15% to 12.5% of the fund in a proposed order filed before the hearing, plus about $3m in expenses, an $18.22m cost reserve, and $50,000 service awards for each of the three lead plaintiffs (per the Authors Alliance docket summary). The court asked for more detail on each of those line items.

Objections have come in across several tracks. Some object that the settlement is too small for what is alleged. Others say the notice campaign steered class members toward filing claims rather than opting out.

Mexican novelist Laura Esquivel, the author of Como agua para chocolate, says she did not receive notice until three weeks after the deadline and that no Spanish-language notice was provided.

Indie novelist Victoria Pinder objects that authors who used a single group copyright registration for many books receive one share rather than one per book, an outcome class counsel has reportedly described as avoiding a ‘windfall'.

The legal architecture under the deal is the one Judge Alsup laid down last June. Training on legitimately acquired books was held to be fair use because it was ‘exceedingly transformative'.

Building a ‘central library' from pirated copies was not, and that ruling, plus class certification, is what pushed Anthropic to the table.

The settlement lands at an awkward moment in Anthropic's balance sheet. The company is in talks to raise $30bn at a $900bn valuation and just put together a $1.5bn pipeline into private equity with Wall Street partners.

The book payout is, in that frame, equal to the company's most recent strategic deal. It is also a one-time charge against a company whose investors are now valuing it at a number with ‘b' in it.

Anthropic has previously said it ‘strongly' disagrees with the underlying ruling but settled to put the issue behind it. The judge did not set a date for her further order. Until she does, the largest known copyright settlement in American history is the largest known proposed copyright settlement in American history.