In 1974 Prime Minister of Pakistan Zulfiqa Bhutto and the Parliament amended the Pakistan Constitution to declare Ahmadis as non-Muslim for the purposes of law. This emboldened extremists (primarily Jamaate Islami and Khatme Nabuwwat) that used this as a pre-text to harass, attack and kill Ahmadis in Pakistan.
Until 1974, Ahmadis were considered to be Muslims. However, through this Constitutional amendment Freedom of Religion guaranteed by the 1973 Pakistan Constitution was rendered entirely impotent for Ahmadis.