D is a law firm. It is controlled by an executive committee. Partners who are not members of the committee have some powers delegated to them for hiring, firing, promotion, and compensation of their subordinates, but all of the nonmember partners are at the committee's mercy. The committee can fire them, promote them, demote them, raise their pay, lower their pay, and so forth. D demoted 32 of its partners. Each of the 32 partners at the time of their demotion had a capital account averaging about $ 400,000. Under the firm's rules, each was liable for the firm's liabilities in proportion to his capital in the firm. Their income was determined by the number of percentage points of the firm's overall profits that the executive committee assigned to each of them. Each served on one or more of the firm's committees, but all these committees are subject to control by the executive committee. P began an investigation to determine if the ADEA had been violated. P issued a subpoena duces tecum seeking a variety of documentation bearing on two distinct areas of inquiry: coverage and discrimination. The ADEA protects employees but not employers. D provided the coverage information but no information relating to discrimination. D claimed that the demotions were due to shortcomings in performance rather than to age. D claimed that before their demotion the 32 had been 'real' partners and so there was no basis for the Commission to continue its investigation. P claimed the demoted partners may have been employees because of the governance structure of the firm. P applied to the district court for an order enforcing the subpoena. The court ordered D to comply in full, and D appealed.