R v Young – 2010 ONSC 4194 (Clark):

[20] The word “substantial” is defined in the Concise Oxford Dictionary, [Oxford, Oxford University Press, 1964], in part, as follows: “having substance, actually existing, not illusory”. The word “likelihood” is defined in the same source, in part, as “being likely”. The word “likely” is defined, in part, as “such as might well happen”. Therefore, so long as the prosecutor demonstrates that the applicant might well commit another offence if admitted to bail, such that the risk is real or tangible, and not simply fanciful or imaginary, she has met her burden.

[21] Moreover, in my view the likelihood of a particular risk materializing cannot be looked at in the abstract. Rather, it must be weighed against the gravity of the harm that will ensue if the risk comes to pass. For example, even a very grave risk that an incorrigible petty thief will shoplift again if granted bail is one that the court might be willing to take when balanced against the accused’s constitutional right to reasonable bail. On the other hand, where the anticipated harm is very grave, a more remote risk may be sufficient meet the test of substantial likelihood. That is of import in this case, where the applicant, for no apparent reason, suddenly engaged in an act of extreme violence, leaving his victim grievously injured and possibly permanently disabled. In the absence of any adequate explanation for this behaviour, of which I will say more when I come to discuss Dr. Sirman’s report, in my opinion the risk is not illusory, but, rather, quite real, that the applicant might well do something similar again if admitted to bail.