537. Restrictions on custodial sentences on persons not legally represented.

A magistrates' court on summary conviction or the Crown Court on committal for sentence or on conviction on indictment may not pass a sentence of imprisonment1 or (in relation to a young offender):


    (1)     pass a sentence of detention2;


    (2)     until a day to be appointed3, pass a sentence of custody for life4 or detention in a young offender institution5;


    (3)     as from that day, pass a sentence of imprisonment on a person who, when convicted, was aged at least 18 but under 216; or


    (4)     make a detention and training order7,

on or in respect of a person who