March 12

… [concerning] the question of the membership of the Universal House of Justice being restricted to men. This, likewise, is a provision of the Sacred Writings, as stated clearly by both ‘Abdu’l-Bahá and the Guardian. It should be viewed in the light of the principle mentioned above, that election to institutions of Bahá’í administration is regarded as a summons to service and not as an accession to power. It is also significant that the Universal House of Justice has itself written that the fact that its membership is restricted to men cannot be used as an indication that men excel women or that the Bahá’í principle of the equality of the sexes is not valid. As you know, it is a mandate of the Universal House of Justice to ensure the establishment of the equality of men and women, and you are undoubtedly aware of the vigor with which the Bahá’ís are putting this into effect. 
(From a letter dated 18 July 2000 written on behalf of the Universal House of Justice to an individual believer)