The defence of accident varies with the nature of the crime. In Criminal Pleading & Practice, Ewaschuck (2nd Edition), the Learned Justice states as follows:
The “so-called” defence of accident varies depending on the nature of the crime. Where the crime involves specific intent, the defence of accident may relate to a denial of a voluntary act causing the prohibited harm or to a denial of intent or purpose to cause the prohibited harm. Where the crime involves general intent or recklessness, the defence of accident generally relates to an unexpected or chance event so unreasonably foreseeable that it exculpates the accused from any blameworthy conduct preceding the accident.
In the criminal law, the term “accident” is used in two senses: an unintended act and an unintended consequence. The former relates to the conduct or actus reus element of an offence, the latter to the fault or mens rea element.
R. v. Ward, 2016 ONCA 984;
R. v. Mathisen, (2008) 2008 ONCA 747 (CanLII), O.J. No. 4382
As with any viable defence, there is no onus of proof on the accused to prove that his conduct was accidental. Where there is an air of reality to the defence, the onus is on the Crown to prove beyond a reasonable doubt that the defence of accident could not succeed.
R. v. Sutherland, (1994) 1993 CanLII 6614 (SK CA), 84 CCC (3d) 484 (Sask. C.A.),