The general powers and duties of the Universal House of Justice, the National Spiritual Assemblies and the Local Spiritual Assemblies and the qualifications for membership are set forth in the Writings of Bahá'u'lláh and 'Abdu'l-Bahá, in the letters of Shoghi Effendi, and in the elucidations of the Universal House of Justice. The major functions of these institutions are outlined in the Constitution of the Universal House of Justice, and in those of the National and Local Spiritual Assemblies.