A longstanding doctrine in corporate law is that where shareholders exercise the power to alter a company’s constitution, they must do so bona fide for the benefit of the company as a whole. This doctrine limiting the right of a shareholder to exercise a personal right in circumstances where the shareholder owes no fiduciary duty to the company is a surprising one. It is suggested in this paper that the true basis for the limitation is to be found in the proper purposes doctrine and that the doctrine is applicable beyond alterations to the constitution. Nevertheless, given the nature of corporations the limitation is a narrow one that has been applied only in extreme cases of shareholder discrimination.