Sidley Austin Brown & Wood is appealing against a subpoena that would force the firm to produce documents relating to the ejection of 32 of its equity partners in the latest stage of the row over alleged discrimination at the top 20 US firm.

The case was launched last year by the US Equal Employment Opportunity Commission (EEOC) because of the actions of the legacy Chicago firm Sidley & Austin, which merged last year with New York’s Brown & Wood.