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. (2) No person shall be qualified to apply for the grant of a certificate or naturalisation, unless he satisfies the President that (a) he is a person of full age and capacity; (b) he is a person of good character; (c) he has shown a clear intention of his desire to be domiciled in Nigeria; (d) he is, in the opinion of the Governor of the State where he is or he proposes to be resident, acceptable to the local community in which he is to live permanently, and has been assimilated into the way of life of Nigerians in that part of the Federation; (e) he is a person who has made or is capable of making useful contribution to the advancement; progress and well-being of Nigeria; (f) he has taken the Oath of Allegiance prescribed in the Seventh Schedule to this Constitution; and (g) he has, immediately preceding the date of his application, either(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. (2) Any registration of a person as a citizen of Nigeria or the grant of a certificate of naturalisation to a person who is a citizen of a country other than Nigeria at the time of such registration or grant shall, if he is not a citizen by birth of that other country, be conditional upon effective renunciation of the citizenship or nationality of that other country within a period of not more than five months from the date of such registration or grant. 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.