The Structure of Defences [Extremely Important]
Every offence has a structure and for purely schematic purposes, Healy wants to describe it as:
Where a PROHIBITED ACT (ACTUS REUS) is committed with a prescribed element of FAULT, those are the constituent elements of GUILT. If these are proved, a conviction will follow.
AR + F = G (unless non-G)
What does it mean to prove it? What does it mean to require the element of voluntary conduct (physical or material element)? What about criminal conduct in the form of omission?
The notion of fault also raises questions.
Foundational idea: the principle of legality is a criterion that must be fulfilled in respect of every offence.
Legality: In order for there to be a valid declaration of criminal liability...
The criminal law cannot have retroactive application
11(b) of Charter
Criminal principles must be sufficiently precise
Frey v. Fedoruk  S.C.R. 517
Frey was a peeping tom on Fedoruk’s land. Fedoruk chased him off with a butcher’s knife and called the police, who arrested Frey without a warrant. Frey sued for damages for false imprisonment.
Can someone be imprisoned for something (being a “peeping tom”) that does not fall within a category of offences known under the criminal law?
No. Frey’s appeal allowed.
People can only be prosecuted for offences known to the criminal law (either in the Criminal Code or by the authority of a reported case).
Conduct that does not fall within any category of criminal offences does not become criminal simply because it provokes violent retributive action in others.
Void for Vagueness and Overbreadth
Before Charter, void for uncertainty was a well-recognized challenge to by-law offences.
Courts here had recoiled from its availability in the case of other types of criminal sanction.