Here are some key facts about Pakistan's law on blasphemy:
-- In 1927, the British colonial rulers of the sub-continent made it a criminal offence to commit "deliberate and malicious acts intended to outrage religious feelings of any class by insulting its religious
belief". The law did not discriminate between religions
-- The law was retained when Pakistan gained independence in 1947 under the rule of the country's moderate founder Mohammad Ali Jinnah
-- Pakistan's late military ruler Mohammed Zia ul-Haq, who was in power for 11 years from 1977, made several additions to its blasphemy laws, including life imprisonment for those defiling or desecrating the Koran
-- In 1984, followers of the minority Ahmadi sect, who believe that Ahmad was a prophet, were banned from calling themselves Muslims, punishable with three years in jail
-- The death penalty for anyone found guilty of defaming Islam was introduced in 1986. Pakistan has yet to execute anyone for blasphemy. Most of those given the death penalty have their sentences overturned or commuted on appeal
-- Ten blasphemy cases were reportedly heard in court in the 58 years between 1927 and 1985, but since then more than 4,000 cases have been handled
-- A Christian woman, Aasia Bibi, was sentenced to hang in Pakistan's central province of Punjab last November after being found guilty of insulting the Prophet Mohammed following a row with Muslim women in her village
-- Lawmaker Sherry Rehman from the ruling Pakistan People's Party sparked fury later that month when she lodged a private member's bill, seeking to abolish the death penalty and clarify the law on blasphemy
-- On December 30, 2010, the PPP-led government announced it had no intention of amending the blasphemy law
-- On December 31, 2010, businesses went on strike across Pakistan in protest over moves to amend the law despite international controversy over Bibi's death sentence
-- On January 5, 2011, moderate politician Salman Taseer was killed by his bodyguard for advocating reform of the blasphemy laws. His assassin was subsequently hailed as a hero, with a number of lawyers offering to represent him for free.
-- On March 2, 2011, gunmen shot dead minorities minister Shahbaz Bhatti, a Catholic, who had vowed to defy death threats in his opposition to the laws.
-- On August 19, 2012, an 11-year old Christian girl, suffering from Down syndrome was arrested for allegedly burning pages of Quran.