In my view, the police had reasonable grounds to believe
that there was an imminent risk to the public peace, and a
substantial risk of harm to the respondent, that justified their
decision to arrest the respondent. The trial judge’s holding to the
contrary is fundamentally flawed and cannot stand.
( ii) Excessive force
 The conclusion that the police had reasonable grounds to
arrest the respondent does not end the inquiry. There is evidence
that, in effecting the arrest, one of the officers may have used
 The fact that the police have lawful authority to arrest an
individual does not authorize them to use whatever force they
may choose to use. The force used must be reasonable. Section
25(1) of the Criminal Code, R.S.C. 1985, c. C-46 reads:
25(1) Every one who is required or authorized by law to do anything in the
administration or enforcement of the law
(a) as a private person,
(b) as a peace officer or public officer,
(c) in aid of a peace officer or public officer, or
(d) by virtue of his office,
is, if he acts on reasonable grounds, justified in doing what he is required or
authorized to do and in using as much force as is necessary for that purpose.
 An officer who uses excessive force in making an arrest
cannot avail him/herself of the protection afforded by s. 25(1).
As the Alberta Court of Appeal said in Crampton v. Walton,
 A.J. No. 178, 2005 ABCA 81, 363 A.R. 216, at para. 43:
Even if the police acted on reasonable grounds in executing the warrant in
an aggressive manner, they will be denied the protection of s. 25(1) if they
used excessive force.
 That said, the police are not to be held to a standard of
perfection in this regard. Allowances must be made for the
nature of the duties that police officers perform and the situa-
tions in which they may have to perform them. The actions of a
police officer are also not to be judged with the benefit of hind-
sight. As LeBel J. said in R. v. Nasogaluak,  1 S.C.R. 206,
 S.C.J. No. 6, 2010 SCC 6, at para. 35:
Police actions should not be judged against a standard of perfection. It
must be remembered that the police engage in dangerous and demanding
work and often have to react quickly to emergencies. Their actions should be
judged in light of these exigent circumstances.