The binding legal principles established are: (1) A court of appeal should guard against eroding the trial court's discretion in sentencing and should only interfere when the discretion was not exercised judicially and properly; (2) Under section 51(1) of the Criminal Law Amendment Act read with Part 1 of Schedule 2, a court is obliged to impose a sentence of life imprisonment for murder committed during a robbery unless there exist substantial and compelling circumstances that justify deviation from the prescribed sentence; (3) Factors such as the accused's age (24 years), loss of a parent, role in the offence, and period in custody prior to sentencing do not, individually or cumulatively, constitute substantial and compelling circumstances where the accused was mature, was the eldest in the group, provided the firearms, and played an active and leading role in planning and executing a violent robbery resulting in deaths.