The U.S. Equal Employment Opportunity Commission has moved to compel testimony about recent conversations between Sidley Austin partners and a former financial director who signed a 1999 letter stating that the firm had a mandatory retirement policy.

Sidley has denied having such a policy in the face of an EEOC suit claiming the Chicago-based law firm discriminated against 31 partners on the basis of age when it demoted them to counsel in 1999. The EEOC has claimed the financial director’s letter “flatly contradicts” the firm’s position.