Independence and the 1960 Constitution
Nigeria became independent on 1 October 1960 under the Constitution of the Federation set out in an Order in Council made by the British Parliament, the product of a series of constitutional conferences through the 1950s that progressively federalized what had been a set of colonial regions into a single country S1S2. That founding document kept Nigeria within a Westminster parliamentary framework: Queen Elizabeth II remained head of state, represented locally by a Governor-General, while day-to-day executive authority sat with a Prime Minister answerable to an elected federal Parliament, a role held at independence by Sir Abubakar Tafawa Balewa S1. The 1960 Constitution organized the country as a federation of three regions — Northern, Western, and Eastern — each with its own premier and regional legislature, a structural choice whose consequences for how power is still divided between Abuja and the states are traced in federal structure of nigeria S1
The 1963 Republican Constitution
Nigeria replaced its independence constitution after only three years: on 1 October 1963 a new Republican Constitution came into force, formally severing the remaining constitutional link to the British Crown and converting the country into a republic within the Commonwealth S1. The change was symbolic and structural but not a wholesale reordering of government — the Westminster parliamentary model, with Balewa remaining Prime Minister, stayed in place — but the ceremonial head of state was now an elected Nigerian President rather than the Queen, an office to which Nnamdi Azikiwe, previously Governor-General, was elected S1. This second constitution is generally treated as completing rather than replacing the work of 1960, since it left the federal structure and the parliamentary system largely intact while resolving the anomaly of a newly independent republic that still nominally answered to a foreign monarch S1
Collapse of the First Republic
The constitutional order established in 1960 and refined in 1963 did not survive the decade. On 15 January 1966, a group of army officers staged a coup that killed Prime Minister Balewa along with the premiers of the Northern and Western regions, after which Major-General Johnson Aguiyi-Ironsi took power and suspended the constitution; a second, countervailing coup on 29 July 1966 killed Ironsi and installed Lieutenant Colonel Yakubu Gowon S1. The Constitution of Nigeria itself still marks that first date as a legal watershed: a clause carried forward into every later version specifies that laws made "on or after 15th January, 1966" are treated as a distinct category from earlier legislation, a textual trace of the day parliamentary government ended S2. The Eastern Region's declaration of an independent Republic of Biafra on 30 May 1967 and the civil war that followed, running from 6 July 1967 to 12 January 1970 and covered in full in nigerian civil war, further entrenched military government and made a new, more centralized constitutional settlement all but inevitable once civilian rule was eventually restored S1
The 1979 Constitution and the Second Republic
After thirteen years of military government, a new constitution took effect on 1 October 1979, the same day Alhaji Shehu Shagari was sworn in as President, opening what is counted as Nigeria's Second Republic S1. The document was the work of a Constitution Drafting Committee of 49 civilian legal experts, whose draft was then reviewed by an elected Constituent Assembly before the outgoing military government finalized it S3. Rather than restoring the Westminster system of 1960 and 1963, the 1979 Constitution replaced it outright with a United States-style presidential system: a President and Vice-President elected directly rather than drawn from a legislature, plus a constitutional "federal character" requirement that cabinet appointments and party structures reflect the country's regional and ethnic diversity, including a rule that a registered political party demonstrate support across two-thirds of the states before contesting a presidential election S1
Renewed military rule and the aborted transitions
The Second Republic lasted barely four years. Shagari won re-election in August 1983 amid widely alleged irregularities, and on 31 December 1983 the military, led by Major General Muhammadu Buhari, seized power again, dissolving all political parties and suspending the 1979 Constitution S1. Successive military governments under Buhari, Ibrahim Babangida, and Sani Abacha held power for sixteen years, during which a further constitution was drafted but never brought fully into force before General Abacha's death on 8 June 1998 opened the way for a final transition S1. His successor, General Abdulsalami Abubakar, announced a transition programme in July 1998 that ran through local, state, and national elections between December 1998 and February 1999, culminating in Olusegun Obasanjo's election as President S1
The 1999 Constitution and the Fourth Republic
The Constitution now in force was signed into law by General Abubakar as the Constitution of the Federal Republic of Nigeria (Promulgation) Decree No. 24 of 1999 on 5 May 1999 and took effect on 29 May 1999, the day Obasanjo was sworn in and military rule ended, opening the Fourth Republic that has now run longer than any of its three predecessors S3S4. Its content, structure, and the five rounds of amendment it has undergone since 1999 are covered in detail in the companion article nigerian constitution rather than repeated here, in keeping with the pattern this article traces: independence in 1960, a republic in 1963, a presidential system in 1979, and the current federal structure since 1999, with each of the first three interrupted by military intervention before the fourth endured S4