The Constitution of the Islamic Republic of Pakistan (Urdu: آئین پاکستان ) is the supreme law of Pakistan. Known as the Constitution of 1973, it was drafted by the government of Zulfikar Ali Bhutto and, following additions by the opposition parties, was approved by the legislative assembly on April 10, 1973. It was Pakistan's first ever constitution by consensus unlike two earlier constitutions, the Constitution of 1956 and the Constitution of 1962.

Pakistan's constitution provides for a parliamentary system of government with the President of Pakistan as head of state and a popularly elected Prime Minister as head of government. Pakistan has a bicameral legislature that consists of the Senate (upper house) and the National Assembly (lower house). Together with the President, the Senate and National Assembly make up a body called the Majlis-e-Shoora (Council of Advisors) or Parliament.

Pakistan became independent from British India in 1947, following its partition. The first document that served as a constitution for Pakistan was the Government of India Act, 1935. The first Pakistani Constituent Assembly was elected in 1947 and after nine years adopted the first indigenous constitution, the short-lived Constitution of 1956.

Pakistan (ⁱ/ˈpækɨstæn/ or ⁱ/pɑːkiˈstɑːn/; Urdu: پاکستان) (Urdu pronunciation: [paːkɪˈst̪aːn] ( listen)), officially the Islamic Republic of Pakistan (Urdu: اسلامی جمہوریۂ پاکستان), is a sovereign country in South Asia. It sits at the crossroads of the strategically important regions of South Asia, Central Asia and the Middle East. It has a 1,046-kilometre (650 mi) coastline along the Arabian Sea and the Gulf of Oman in the south and is bordered by India to the east, Afghanistan to the west and north, Iran to the southwest and China in the far northeast. It is separated from Tajikistan by Afghanistan's narrow Wakhan Corridor in the north, and it shares a marine border with Oman.

The territory of modern Pakistan was the site of several ancient cultures, including the Neolithic Mehrgarh and the Bronze Age Indus Valley Civilisation, and has undergone invasions or settlements by Hindu, Persian, Indo-Greek, Islamic, Turco-Mongol, Afghan and Sikh cultures. Thus the area has been ruled by numerous empires and dynasties, including the Indian Mauryan Empire, the Persian Achaemenid Empire, the Arab Umayyad Caliphate, the Mongol Empire, the Mughal Empire, the Durrani Empire, the Sikh Empire and the British Empire. As a result of the Pakistan Movement led by Muhammad Ali Jinnah and India's struggle for independence, Pakistan was created in 1947 as an independent nation for Muslims from the regions in the east and west of India where there was a Muslim majority. Initially a dominion, Pakistan adopted a new constitution in 1956, becoming an Islamic republic. A civil war in 1971 resulted in the secession of East Pakistan as the new country of Bangladesh.

The Constitution of India (Hindi: भारतीय संविधान; see also names in the other official languages) is the supreme law of India. It lays down the framework defining fundamental political principles, establishes the structure, procedures, powers, and duties of government institutions, and sets out fundamental rights, directive principles, and the duties of citizens. It is the longest written constitution of any sovereign country in the world, containing 444 articles in 24 parts, 12 schedules and 97 amendments. Besides the English version, there is an official Hindi translation. Bodhisattva Dr. Babasaheb Ambedkar[bhimrao ramji Ambedkar] is Chief Architect of Indian Constitution.

The Constitution was enacted by the Constituent Assembly on 26 November 1949, and came into effect on 26 January 1950. The date 26 January was chosen to commemorate the Purna Swaraj declaration of independence of 1930. With its adoption, the Union of India officially became the modern and contemporary Republic of India and it replaced the Government of India Act 1935 as the country's fundamental governing document. The Constitution declares India to be a sovereign, socialist, secular, democratic republic, assuring its citizens of justice, equality, and liberty, and endeavours to promote fraternity among them. The words "socialist" and "secular" were added to the definition in 1976 by constitutional amendment. India celebrates the adoption of the constitution on 26 January each year as Republic Day.