May 13

In a letter dated 9 March 1965, the Universal House of Justice stresses the "profound difference" that exists between the "interpretations of the Guardian and the elucidations of the House of Justice in exercise of its function to 'deliberate upon all problems which have caused difference, questions that are obscure, and matters that are not expressly recorded in the Book."' (Wellspring of Guidance, p. 52) Among these is the outlining of such steps as are necessary to establish the World Order of Bahá'u'lláh on this earth. The elucidations of the Universal House of Justice stem from its legislative function, while the interpretations of the Guardian represent the true intent inherent in the Sacred Texts. The major distinction between the two functions is that legislation with its resultant outcome of elucidation is susceptible of amendment by the House of Justice itself, whereas the Guardian's interpretation is a statement of truth which cannot be varied. 
(From a letter dated 25 October 1984 written on behalf of the Universal House of Justice to an individual believer; ‘Messages from the Universal House of Justice, 1963-1986)