Nigeria's first constitutions were enacted by order in council during the colonial era, when the country was administered as a Crown Colony. The constitutions enacted during this period were those of 1913, 1922, 1946, 1951 and 1954. In 1946 a new constitution was approved by Westminster and promulgated in Nigeria. Although it reserved effective power in the hands of the Governor-General and his appointed Executive Council, the so-called Richards Constitution provided for an expanded Legislative Council empowered to deliberate on matters affecting the whole country. Separate legislative bodies, the houses of assembly, were established in each of the three regions to consider local questions and to advise the lieutenant governors. The introduction of the federal principle, with deliberative authority devolved on the regions, signaled recognition of the country's diversity. Although realistic in its assessment of the situation in Nigeria, the Richards Constitution undoubtedly intensified regionalism as an alternative to political unification. The pace of constitutional change accelerated after the promulgation of the Richards Constitution. It was suspended in 1950 against a call for greater autonomy, which resulted in an inter-parliamentary conference at Ibadan in 1950. The conference drafted the terms of a new constitution. The so-called Macpherson Constitution, after the incumbent Governor-General, John Stuart Macpherson, went into effect the following year. The most important innovations in the new charter reinforced the dual course of constitutional evolution, allowing for both regional autonomy and federal union. By extending the elective principle and by providing for a central government with a Council of Ministers, the Macpherson Constitution gave renewed impetus to party activity and to political participation at the national level. But by providing for comparable regional governments exercising broad legislative powers, which could not be overridden by the newly established 185-seat federal House of Representatives, the Macpherson Constitution also gave a significant boost to regionalism. Subsequent revisions contained in the Lyttleton Constitution, named for Oliver Lyttelton, 1st Viscount Chandos and enacted in 1954, firmly established the federal principle and paved the way for independence.
The 1979 constitution, which brought in the Second Republic, abandoned the Westminster system in favour of an American-style presidential system, with a direct election, directly-elected. To avoid the pitfalls of the First Republic, the constitution mandated that political parties and Federal Executive Council positions reflect the "federal character" of the nation: political parties were required to be registered in at least two-thirds of the States of Nigeria or states, and each state had to have at least one member of the cabinet from it.
1993 constitution (Third Republic)
The 1993 constitution was intended to see the return of democratic rule to Nigeria with the establishment of a Third Republic, but was never fully implemented, and the military resumed power until 1999
1999 presidential constitution (Fourth Republic)
The 1999 constitution restored democratic rule to Nigeria, and remains in force today. In January 2011, two amendments of the 1999 constitution were signed by President Olusegun Obasanjo, the first modifications since the document came into use in 1999.
