23Remand and committal of persons under 21
(1)Where a court remands or commits for trial or for sentence a person under 21 years of age who is charged with or convicted of an offence and is not released on bail, then, except as otherwise expressly provided by this section, the following provisions shall have effect, that is to say—
(a)subject to the following paragraph, if he is under 16 years of age the court shall commit him to the local authority in whose area the court is situated, and the authority shall have the duty of placing him in a suitable place of safety chosen by the authority instead of committing him to prison ;
(b)if he is a person of over 16 years of age, or a child under 16 years of age but over 14 years of age who is certified by the court to be unruly or depraved, and the court has been notified by the Secretary of State that a remand centre is available for the reception from that court of persons of his class or description, he shall be committed to a remand centre instead of being committed to prison.
(2)Where any person is committed to a local authority or to a remand centre under any provision of this Act, that authority or centre shall be specified in the warrant, and he shall be detained by the authority or in the centre for the period for which he is committed or until he is liberated in due course of law.
(3)Where any person has been committed to a local authority under any provision of this Act, the court by which he was committed, if the person so committed is not less than 14 years of age and it appears to the court that he is unruly or depraved, may revoke the commitment and commit the said person—
(a)if the court has been notified that a remand centre is available for the reception from that court of persons of his class or description, to a remand centre; and
(b)if the court has not been so notified, to a prison.
(4)Where, in the case of a person under 16 years of age who has been committed to prison or to a remand centre under this section, the sheriff is satisfied that his detention in prison or a remand centre is no longer necessary, he may revoke the commitment and commit the person to the local authority in whose area the court is situated, and the authority shall have the duty of placing him in a suitable place of safety.