Reasonable and probable grounds to demand a breath test

R. v. Bush, 2010 ONCA 554, released on-line today, sets out the test for demanding a driver perform a breath test as follows:

[46]          In the context of a breath demand, the reasonable and probable grounds standard is not an onerous test:  see R. v. Wang, 2010 ONCA 435 at para. 17.  It must not be inflated to the context of testing trial evidence.  Neither must it be so diluted as to threaten individual freedom:  Censoni at para. 43.  

[47]          There is no necessity that the defendant be in a state of extreme intoxication before the officer has reasonable and probable grounds to arrest:  R. v. Deighan, [1999] O.J. No. 2413 (C.A.) at para. 1.  Impairment may be established where the prosecution proves any degree of impairment from slight to great:  R. v. Stellato (1993), 12 O.R. (3d) 90 (C.A.), aff'd [1994] 2 S.C.R. 478.  Slight impairment to drive relates to a reduced ability in some measure to perform a complex motor function whether impacting on perception or field of vision, reaction or response time, judgment, and regard for the rules of the road:  Censoni at para. 47.

[48]          The test is whether, objectively, there were reasonable and probable grounds to believe the suspect's ability to drive was even slightly impaired by the consumption of alcohol:  see R. v. Stellato (1993), 78 C.C.C. (3d) 380 (Ont. C.A.), aff'd [1994] 2 S.C.R. 478; Moneno-Baches and Wang, at para. 17.  Where appellate courts are called upon to review the trial judge's conclusions as to whether the officer objectively had reasonable and probable grounds, the appellate court must show deference to the trial judge's findings of fact although the trial judge's ruling is a question of law reviewable on the standard of correctness:  Wang at para. 18.