143. (1) When any person subject to this Act has been convicted by a court martial of any offence, the Government or the Chief of Army Staff or any officer not below the rank of ¹[Brigadier General] empowered in this behalf by the Chief of Army Staff may-(i) either without conditions or upon any conditions which the person sentenced accepts, pardon the person or remit the whole or any part of the punishment awarded; or(ii) mitigate the punishment awarded or commute such punishment for any less punishment or punishments mentioned in this Act: Provided that a sentence of transportation shall not be commuted for a sentence of rigorous imprisonment for a term exceeding the term of transportation awarded by the court, and a sentence of rigorous imprisonment shall not be commuted for a sentence of detention for a term exceeding the term of rigorous imprisonment awarded by the court. (2) If any condition on which a person has been pardoned or a punishment has been remitted is, in the opinion of the authority which granted the pardon or remitted the punishment, not fulfilled, such authority may cancel the pardon or remission, and thereupon the sentence of the court shall be carried into effect as if such pardon had not been granted or such punishment had not been remitted: Provided that, in the case of a person sentenced to transportation, rigorous imprisonment, or detention, such person shall undergo only the unexpired portion of his sentence. (3) When under the provisions of sub-section (5) of section 62 a non-commissioned officer is deemed to be reduced to the ranks, such reduction shall, for the purposes this section, be treated as a punishment awarded by sentence of a court martial.