[16] Mulk practiced law for over 17 years at the Peshawar High Court where he built his reputation for competency and a positive approach toward the cases he contested.

[13][17] Justice Mulk presided and heard the Mukhtār Mā'ī case—the controversial and highly publicized case regarded a gang rape that occurred in 2002.

[18] He reportedly penned his judgement that "Jirgas cannot be allowed to arbitrarily punish in the form of watta satta marriages and gang-rape to settle disputes without being answerable to the law.

[18] On 2 November 2007, Barrister Aitzaz Ahsan submitted an application to the Supreme Court asking that the government be restrained from imposing martial law in Pakistan.

[19] Reviewing the application, a seven-panel bench in Supreme Court of Pakistan issued an injunction against the imposition of state emergency on 3 November 2007.

[19] Others included Senior Justices Nasir-ul-Mulk; Fayyaz Ahmad; Bhagwandas; Javaid Iqbal; Shakirullah Jan; Ghulam Rabbani.

[13] A strong, publicly instigated lawyer's movement which enjoyed support from PML(N) forced President Musharraf to resign in a threat to face impeachment.

[16] If Pakistan's state institutions differ on implementation of the Constitution, the Supreme Court has the right to intervene, hinting at the same..He was appointed as Chief Justice on 6 July 2014.

[21] In consequence of their decision, Mulk, in an oath taking ceremony at Presidency Palace, was sworn in as caretaker prime minister of Pakistan.

[23] During his first few days as prime minister, he instructed the legal team of government to file an appeal against a Lahore High Court decision which has annulled the nomination papers for elections.