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
3) Subject to subsections (4) and (5), a person is not justified for the purposes of subsection (1) in using force that is intended or is likely to cause death or grievous bodily harm unless the person believes on reasonable grounds that it is necessary for the self-preservation of the person or the preservation of any one under that person's protection from death or grievous bodily harm.