Nigerian nationality law

Nigerian nationality law is the law of Nigeria which concerns citizenship and other categories of Nigerian nationality.
Requirements.
(1) The following are ways to gain citizenship in Nigeria
By birth-namely-
(a) Every person born in Nigeria after the date of independence (October 1, 1960), either of whose parents or any of whose grandparents belongs or belonged to a community indigenous to Nigeria;
Provided that a person shall not become a citizen of Nigeria by virtue of this section if neither of his parents nor any of his grandparents was born in Nigeria.
(b) Every person born outside Nigeria either of whose parents is a citizen of Nigeria.
(2) In this section, "the date of independence" means the 1st day of October 1960.
By registration:
26. (1) Subject to the provisions of section 28 of this Constitution, a person to whom the provisions of this section apply may be registered as a citizen of Nigeria, if the President is satisfied that -
(2) The provisions of this section shall apply to-
(a) Any woman who is or has been married to a citizen of Nigeria or every person of full age and capacity born outside Nigeria any of whose grandparents is a citizen of Nigeria.
By naturalization:
27. (1) Subject to the provisions of section 28 of this Constitution, any person who is qualified in accordance with the provisions of this section may apply to the President for the same of a certificate of naturalisation.
(i) Resided in Nigeria for a continuous period of fifteen years; or
(ii) Resided in Nigeria continuously for a period of twelve months, and during the period of twenty years immediately preceding that period of twelve months has resided in Nigeria for periods amounting in the aggregate to not less than fifteen years.
28. (1) Subject to the other provisions of this section, a person shall forfeit forthwith his Nigerian citizenship if, not being a citizen of Nigeria by birth, he acquires or retains the citizenship or nationality of a country, other than Nigeria, of which he is not a citizen by birth.
29. (1) Any citizen of Nigeria of full age who wishes to renounce his Nigerian citizenship shall make a declaration in the prescribed manner for the renunciation.
(2) The President shall cause the declaration made under subsection (1) of this section to be registered and upon such registration, the person who made the declaration shall cease to be a citizen of Nigeria.
(3) The President may withhold the registration of any declaration made under subsection (1) of this section if-
(a) The declaration is made during any war in which Nigeria is physically involved; or
(b) In his opinion, it is otherwise contrary to public policy.
(4) For the purposes of subsection (1) of this section.
(a) "full age" means the age of eighteen years and above;
(b) Any woman who is married shall be deemed to be of full age.
30. (1) The President may deprive a person, other than a person who is a citizen of Nigeria by birth or by registration, of his citizenship, if he is satisfied that such a person has, within a period of seven years after becoming naturalized, been sentenced to imprisonment for a term of not less than three years.
(2) The President shall deprive a person, other than a person who is citizen of Nigeria by birth, of his citizenship, if he is satisfied from the records of proceedings of a court of law or other tribunal or after due inquiry in accordance with regulations made by him, that -
(a) The person has shown himself by act or speech to be disloyal towards the Federal Republic of Nigeria; or
(b) The person has, during any war in which Nigeria was engaged, unlawfully traded with the enemy or been engaged in or associated with any business that was in the opinion of the president carried on in such a manner as to assist the enemy of Nigeria in that war, or unlawfully communicated with such enemy to the detriment of or with intent to cause damage to the interest of Nigeria.
31. For the purposes of this Chapter, a parent or grandparent of a person shall be deemed to be a citizen of Nigeria if at the time of the birth of that person such parent or grandparent would have possessed that status by birth if he had been alive on the date of independence; and in this section, "the date of independence" has the meaning assigned to it in section 25 (2) of this Constitution.
32. (1) The president may make regulations, not inconsistent with this Chapter, prescribing all matters which are required or permitted to be prescribed or which are necessary or convenient to be prescribed for carrying out or giving effect to the provisions of this Chapter, and for granting special immigrant status with full residential rights to non-Nigerian spouses of citizens of Nigeria who do not wish to acquire Nigerian citizenship.
(2) Any regulations made by the president pursuant to the provisions of this section shall be laid before the National Assembly
NIGERIA
CITIZENSHIP: Citizenship is based upon the Constitution of the Federal Republic of Nigeria, dated 1989. (UKC-Commonwealth Nation) 
Those born before or on the date of independence, October 1, 1960, whose parents or grandparents were born in Nigeria and who were legally residing in Nigeria at the time, are considered citizens of Nigeria. 
BY BIRTH: Birth within the territory of Nigeria does not automatically confer citizenship. 
BY DESCENT: Child, at least one of whose parents is a citizen of Nigeria, regardless of the child's country of birth. 
REGISTRATION: The following persons are eligible to become citizens through registration: A foreign woman who marries a citizen of Nigeria. Person who is of adult age (17), born outside Nigeria, any of whose grandparents is or was a citizen of Nigeria. A foreign child adopted by Nigerian parents. 
BY NATURALIZATION: Nigerian citizenship may be acquired upon fulfillment of the following conditions: Person is of full age (17), has resided in Nigeria for at least 15 years, is of good character, plans to remain in Nigeria, is familiar with Nigerian language and customs, has a viable means of support, and has renounced previous citizenship.
LOSS OF CITIZENSHIP:
VOLUNTARY: Voluntary renunciation of Nigerian citizenship is permitted by law. Contact the Embassy for details and required paperwork. 
INVOLUNTARY: The following are grounds for involuntary loss of Nigerian citizenship: Registered or Naturalized citizen voluntarily acquires the citizenship of a foreign country. Naturalized citizen, before seven years of residence, sentenced to prison for three years or more. Registered or Naturalized citizen is convicted of acts of disloyalty to the Federal Republic of Nigeria.
Dual nationality.
Nigerian nationality law allows dual nationality of people of Nigerian descent either through birth or parentage. They are also allowed to hold public office in Nigeria.
Some in Nigeria feel that dual nationality damages nationality unity of the country.
Nigeria and the Commonwealth of Nations.
Nigerians are also Commonwealth citizens.
Visa requirements of Nigerian citizens.
Visa requirements for Nigerian citizens are administrative entry restrictions by the authorities of other states placed on citizens of Nigeria. In 2016, Nigerian citizens had visa-free or visa-on-arrival access to 45 countries and territories, ranking the Nigerian passport 92nd in the world according to the Visa Restrictions Index.