Schedule B - Constitution Act, 1982 (79)
PART I - Canadian charter of rights and freedoms
Legal Rights
11. Any person charged with an offence has the right
...
i) if found guilty of the offence and if the punishment for the offence has been varied between the time of commission and the time of sentencing, to the benefit of the lesser punishment.
Sentencing - national proceedings
Determination of sentence - national proceedings
EDIT.