Pakistan's President Asif Ali Zardari Monday signed into law sweeping constitutional reforms that strip him of key powers in a move to bolster parliamentary democracy weakened by military rule. Apart from all the provincial chief ministers, governors, federal ministers and heads of almost all the parliamentary parties, the main opposition leader and Zardari's principal critic, Nawaz Sharif, also attended the historic event The amendment rolls back decades of meddling by military rulers and removes the head of state's power to sack the prime minister, appoint heads of the armed forces, unilaterally declare emergency rule and dissolve parliament. “My head bows in gratitude before Allah for the opportunity to sign the 18th Constitutional Amendment Bill,” Zardari said. “It is indeed a great honor for me to sign into law this bill that seeks to undo the undemocratic clauses introduced into the Constitution by undemocratic rulers.” Prime Minister Yousaf Raza Gilani will assume executive power in a move that could help ease simmering political instability in the country. Gilani also hailed the signing of the bill as a “momentous occasion” and praised Zardari's “magnanimity”. The bill also abolishes a clause barring the election of a prime minister for more than two terms. This would allow the popular Sharif, who was toppled by Musharraf in 1999, to become prime minister again. The amendments will effectively make Zardari a titular head of state who can only formally appoint heads of the armed forces, dissolve the National Assembly and appoint provincial governors on the advice of the prime minister. The 18th amendment also renames North West Frontier Province, a throwback to the British colonial era, Khyber Pakhtunkhwa.