The time spent in custody by an offender on unrelated charges can be considered in a limited way in determining a fit sentence.

As Justice Rosenberg stated in R. v. Wilson, 2008 ONCA 510, 236 C.C.C. (3d) 285 at para. 46, “a sentencing judge is entitled to take into account time spent serving another sentence as part of the complete picture for understanding a particular offender.” Justice Rosenberg cited as one example a situation where an offender with a drug problem received treatment while serving his sentence. 

However, it would be an error in law for the sentencing judge to go beyond this limited analysis and grant credit for the time served on unrelated charges.

R. v. Pammett, 2016 ONCA 979 at para 29.

Giving an offender credit for pretrial custody for unrelated charges would permit an accused to “bank” time spent in custody. As Rosenberg J.A. observed in R. v. Wilson, at para. 45:

But, at the end of the day when it comes time to sentence an offender the court can only take into account factors that relate to the particular offence under consideration. The fact that an offender, like the appellant, still happens to be in the appeal system when a flaw in relation to a totally unrelated conviction comes to light is not, in my view, a principled reason for giving that offender credit for the time he or she spent serving the sentence for that unrelated conviction.

R. v. Wilson, 2008 ONCA 510, 236 C.C.C. (3d) 285.

Justice Rosenberg recognized that in R. v. Reid, 2005 CanLII 14964 (Ont. C.A.) and R. v. Tsai (2005), 198 C.C.C. (3d) 533 (Ont. C.A.), the Court of Appeal for Ontario appears to have given some credit for pretrial custody on another offence. However, he noted, at para. 50, that in “both cases the accused was refused bail on the second set of charges (the charges that were later withdrawn) because he was already on bail for the first set of charges. Thus, in part, the time spent in custody for the withdrawn set of charges could be attributed to the first set of offences.” Justice Rosenberg also pointed out that in neither case was the appellant seeking to have the court retroactively take into account time served on another charge.