What Constitutes Self-defence And To What Extent

To what extent can I use self-defence in Canada against an unarmed assailant?

My answer is more of a moral response. I have no idea what the laws in Canada are for those situations. For credibility, have been in many fights myself for being of asian descent and having quite a hot head. Ok. Back to the point, fight him to the point that he can no longer harm you. There is no use in harming him further as he poses no threat to you. Make sure he is on the ground and walk away. If you are at a school, tell the teacher and come clean(there is no use doing anything else as you will still get in trouble). If you are anywhere else, just leave.

To what extent of danger must you be in before self-defense is considered a lawful action?

Not a lawyer, so this aint legal advice...According to my reading of the CA statute, you can use reasonable force to protect yourself from any unlawful attack.  assault is conduct that would cause a reasonable person to be in fear of unwanted and unlawful physical contact, so, say you're having a disagreement with someone, and he pokes his finger at you as if to poke your chest, and you slap his hand away to prevent him touching you. He committed assault by making you afraid he was going to make unwanted unlawful contact (poking your chest with his finger), and you used reasonable force (slapping his hand aside) to prevent it. So, as you see, you have the legal right to prevent ANY extent of UNLAWFUL physical CONTACT with yourself, it doesn't even have to rise to the level of actual danger. Be advised, however, that your response MUST BE REASONABLE. For example, lets go back to the guy poking at you with his finger. Say he actually pokes you in the chest while you're arguing, he has committed assault AND battery by touching you, but you can't break his jaw, that would be using more than reasonable force. But you probably could escalate to pushing him back and taking a defensive posture, while warning him to desist. If he came at you after that, it would probably be reasonable for you to assume more drastic defense was called for. Be advised that in ANY use of force, you may very well be defending yourself after the fact in court, so don't just read some posts on Quora and call it good. Go to your local law library, as I did, and look up the laws for where you live, and read them carefully, make sure you understand them. Better one boring afternoon puzzling it out than jail time for not knowing it. Self defense is legal everywhere, but fighting is a jail time offense. Sometimes the difference between the two is a little knowledge. Good luck.

What event prompted 13+ states to extend their castle (self defence) laws in late 2005?

The people of those states wanted a castle law , the event of it was probably violent crime and criminals getting away with those crimes

Is there an extent where self defense may be necessary in schools?

Self defense may be necessary anyway. And yet, by being prepared and unafraid (even when I had reason to be afraid), I have always walked out of situations without having to exert myself.If you are going to learn self defense, then learn something with the idea of being thereby in a position to teach an attacker, secondarily, at least to be able to control the attacker, and, if the worst happens then to be able to de-escalate the level of violence. How so? The old Kung Fu TV series had a scene in the pilot episode in which the young Kaine and other young students receive instruction:"Perceive the way of nature and no force of man can harm you. Do not meet a wave head on: avoid it. You do not have to stop force: it is easier to redirect it. Learn more ways to preserve rather than destroy. Avoid rather than check. Check rather than hurt. Hurt rather than maim. Maim rather than kill. For all life is precious nor can any be replaced." - Master Kan (Original Pilot Movie)Somebody named David Chow did the advising for this session, and he really knew the philosophy of the ancient Chinese.One of my teachers in Taiwan, Wei Xiao-tang, taught us that if you can put an attacker firmly under your control he will normally leave off his attack and quit the field unless he is under the influence of some drug.Particularly in a school system, where you have some backup and where hopefully there are no psychos running around loose, it should be enough to learn the skills of defense and control. (I should caution you that you may get in trouble for good reason if you put an attacker down with enough force to injure him/her.) So rather than something like karate, which tends to put the purely defensive moves in a subsidiary ranking, I would think that you ought to find a school that teaches Aikido, or its Chinese near equivalent, Qin-na.Just for fun, here is a Chinese version of the Kung Fu stuff, but starting from “Learn more ways.”

To what extent do people in the UK have a right to self-defense?

As it has been said, it depends on the circumstances but it is strongly advised as a last resort.If you can prove that you used proportionate force to defend oneself or another against a direct attack then you will not be convicted.You are always arrested, whatever force used, so you must prove this to the jury.I don't know about lethal force, the circumstances would have to be exceptional. If not, you will be convicted of murder or at the very least, manslaughter.No offensive weapon or tool may be carried without a proveable, constructive, licenced use. No blades above 3 inches may be carried.Of course, we're intelligent not to allow the buying of guns to anybody, except to farmers - to protect their flock from animals not people -sportsmen, hunters etc.A comprehensive set of rules is a Google search away.And if you do have a gun, you must own a gun cabinet, you are subject to random police checks (who will always be notified of your licence) and you are NOT ALLOWED TO CARRY OPENLY! You will be taken down by armed police and detained indefinitely under the Terrorism Act 2000. You will also permanently lose your licence.