Section 158: Duration of sentence of imprisonment

(1) Where a person serving a sentence of imprisonment becomes unlawfully at large during the currency of the sentence, then, in calculating the period for which he is liable to be imprisoned in pursuance of the sentence, no account shall be taken of time elapsing during the period beginning with the day on which he became at large and ending with the day on which, as a person having become unlawfully at large, he is taken into Army, Naval or Air Force custody or the custody of a civil authority or (not having been taken into custody) he returns to the place in which he was imprisoned before he became unlawfully at large.
(2) If a person to whom subsection (1) of this section refers, satisfies such authority as may be specified in that behalf by or under Imprisonment Rules that during the period beginning with the day on which he became at large and ending with the day he is taken into custody under that subsection, he was-
(a) in the custody of a civil authority; or
(b) if and in so far as Imprisonment Rules so provide, in the custody of any Army, Naval or Air Force authority of any country or territory outside Nigeria as respects which arrangements have been made under section 166 of this Act,
otherwise than on account of an offence committed by him while unlawfully at large, that period shall not be disregarded in calculating the period for which he is liable to be imprisoned or detained in pursuance of the sentence imposed under this Act.
(3) In subsections (1) and (2) of this section, "civil authority" means a civil authority (whether of the Federation or of any country or territory outside Nigeria) authorised by law to detain persons and includes a police officer.
(4) Without prejudice to the provisions of subsection (1) of this section, where a person serving a sentence of imprisonment has in accordance with Imprisonment Rules been temporarily released on compassionate grounds, then in calculating the period for which he is liable to be imprisoned in pursuance of the sentence, no account shall be taken of the time elapsing during the period beginning with the day after that on which he is released and ending with the day on which he is required to return to custody.
(5) A person who for any period is released as mentioned in subsection (4) of this section or who is otherwise allowed, in pursuance of Imprisonment Rules, out of military custody for any period or subject to any condition shall, on failure to return at the expiration of the period or to comply with the conditions, be treated for the purposes of subsection (1) of this section as being unlawfully at large.
(6) A person serving a sentence of imprisonment in civil custody who, after being temporarily released under civil law, is at large at any time during the period for which he is liable to be detained in civil custody in pursuance of the sentence, shall be deemed to be unlawfully at large if the period for which he was temporarily released has expired or if an order recalling him has been made in pursuance of civil law.
(7) A reference in subsection (6) of this section to release or recall under civil law is a reference to release or recall in pursuance of the law of the country or territory in which the person is serving his sentence.