however, there's a difference between self-defence and assault. if you're not defending yourself anymore, it's no longer self defence. this would be things like shooting at people that are trying to flee.
my take on the issue in kawartha lakes is that the charges by police are unjustified, and the individual will likely have the charges dropped, or be acquitted. that looks like self defence to me. this is why we have courts - cops are quite often very dumb people, and frequently don't understand the law very well.
in context, the officer should have sought a warrant for the individual's arrest. that is the step that police skip too often, and need to be retrained to do instinctively. police officers should not be making decisions like this independent of the courts. the courts should be doing all of the thinking; the cops are just dumb muscle, sent out as enforcement. they aren't paid to think, and should be explicitly forbidden from trying.
i doubt a judge would have approved a warrant in this case, and that would have been the end of it. as it is, i hope the process of acquittal is not too long or too inconvenient.
the media commenters have apparently all forgotten that the individual is innocent until proven guilty, and entitled to due process of law.