Onus of Proof
The onus of proof is the legal burden of establishing the elements of an offence. In Canadian criminal law, the onus rests on the Crown, and the standard is proof beyond a reasonable doubt for every essential element. The presumption of innocence under section 11(d) of the Charter underwrites the rule: the accused does not need to prove anything; the Crown must prove guilt.
Legal vs. evidentiary burden
Two related but distinct concepts apply. The legal burden (or persuasive burden) is the obligation to prove the matter to the required standard. The evidentiary burden is the obligation to put forward enough evidence to raise an issue for consideration. The legal burden almost always rests with the Crown in criminal cases. The evidentiary burden can shift to the accused on certain defences — once the defence raises an air of reality, the Crown must disprove the defence beyond a reasonable doubt.
When the onus shifts
There are limited situations where the onus of proof — not just the evidentiary burden — shifts to the accused: reverse onus bail hearings under section 515(6), where the accused must justify release; certain statutory presumptions, such as the section 348(2) presumption arising from break-and-enter conduct; the defence of mental disorder under section 16(2), where the accused must prove on a balance of probabilities; and a small number of regulatory and licensing-style offences.
Reverse onus and the Charter
Statutory provisions that reverse the onus on essential elements of an offence have been subject to Charter scrutiny. The Supreme Court has held that reverse onus provisions on essential elements of an offence engage section 11(d) and can survive only if justified under section 1. Reverse-onus bail provisions have generally been upheld; reverse-onus provisions on substantive guilt are scrutinized more strictly.
Standards
Beyond a reasonable doubt is the criminal standard — much closer to absolute certainty than to a balance of probabilities. Balance of probabilities is the civil standard and applies to many ancillary criminal questions: voluntariness of confessions (Crown burden), Charter motions (defence burden), and certain defences with a reverse onus. Reasonable suspicion and reasonable grounds are investigative thresholds, lower still, used in detention, arrest, and search analyses.
Strategic implications
The onus is the structural advantage that drives criminal defence work. The defence does not need to prove innocence; it only needs to leave reasonable doubt on any essential element. Mass Tsang's criminal lawyers approach every file with the burden in mind — identifying where the Crown's evidence falls short of beyond a reasonable doubt and building toward an acquittal.
Related glossary terms
