Every one who, in committing an assault... (b) causes bodily harm to the complainant...is guilty of an indictable offence and liable to imprisonment for a term not exceeding ten years or an offence punishable on summary conviction and liable to imprisonment for a term not exceeding eighteen months.On a charge of assault causing bodily harm, the Crown may elect to proceed by indictment or summary conviction process. The term bodily harm is defined at section 2 of the Criminal Code as follows:
bodily harm means any hurt or injury to a person that interferes with the health or comfort of the person and that is more than merely transient or trifling in nature
The definition of bodily harm is designed to be broad and cover a wide range of injuries. Generally, a red mark or slight bruise would not fall into the category, as those injuries would be considered transient or trifling. However, the injury caused need not be terribly "intense" in degree. For example, the case law has found that cutting a person's hair can constitute "bodily harm" depending on the circumstances (i.e. to impose a lousy hair cut on an ex-girlfriend as an act of malice). More generally, however, bodily harm encompasses cuts, fractures, or more serious bruising that is more than simply transient or trifling in nature. Each case is of course, determined on its own facts.
Since assault causing bodily harm is a "general intent" offence, it does not need to be proven by the Crown that the accused "intended" to cause the bodily harm. The Crown needs to demonstrate that an assault occurred, which resulted in bodily harm. Thus, on person may strike another, and the result may be merely a red mark, yielding the lesser charge of assault simpliciter pursuant to section 266. Another person may issue the same strike, but cause a missing tooth, and incidentally be charged with assault causing bodily harm, despite the fact that the same amount of force was used as the first perpetrator. Although the intent of both accused was to merely strike the victim once, the difference in degree of damage is what determines whether the augmented charged of "causing bodily harm" is merited.