After the abrogation of the Constitution of 1962, Yahya Khan needed a legal framework to hold elections. In April and July 1969, he held discussions with prominent political party leaders to learn their point of view. Most of them asked for the revival of the Constitution of 1956 on the ground that its abrogation had been unlawful, and the country should return to the constitutional position prevailing on the eve of the 1958 coup. Yahya Khan initially agreed with this opinion, but had to change his stance due to opposition from the Awami League.
Not being well versed in constitutional affairs, he appointed a team to draft a new constitutional formula. He voiced his ideas about the constitutional issues in his broadcast address to the nation on November 28, 1969. The formula was officially issued on March 30, 1970, and is known as the Legal Framework Order of 1970. According to this order, One Unit was dissolved in West Pakistan and direct ballot replaced the principle of parity.
The National Assembly was to consist of 313 seats, including 13 seats reserved for women. Women were also allowed to contest the elections from general seats. The distribution of seats was to be as follows:
- East Pakistan: 162 general and 7 reserved seats
- Punjab: 82 general and 3 reserved seats
- Sindh: 27 general and 1 reserved seat
- N. W. F. P.: 18 general and 1 reserved seat
- Baluchistan: 4 general and 1 reserved seat
- Centrally Administered Tribal Areas: 7 general seats