Guardian of the Faith has been made the permanent head of the UHJ

"Though the Guardian of the Faith has been made the permanent head of so august a body he can never, even temporarily, assume the right of exclusive legislation. He cannot override the decision of the majority of his fellow-members, but is bound to insist upon a reconsideration by them of any enactment he conscientiously believes to conflict with the meaning and to depart from the spirit of Baha’u’llah’s revealed utterances."

(Shoghi Effendi, The World Order of Baha’u’llah, p. 150)