would u be charged if u accidently paralyzed him ?

Where do you live?
In canada we are required by law to verbally warn assailants 3 times before its considered self defense and in a lot of cases both parties can end up with charges.

If you have the ability to snap someone's neck you obviously have self defense skills and would be self defense with unnecessary force
It's like shoting a guy in the head instead of the leg

I'm glad to see that you're seeing things eye to eye now. Don't go around snapping necks. That's not nice.

Depends on the state.

This.

More times than not you're going to get fucked for this. If you're that much more physically powerful than your opponent, the court is going to destroy you for not using more reasonable measures in dealing with the altercation.

Too many details left unsaid. Are you also in a vehicle? Does the person have a weapon? Does the province you live in support self defense? A lot of provinces/states have requirements that you make an effort to avoid the situation. In Iowa for example we are a stand your ground state so I have no duty to retreat from any place I have the right to be, including public places. However if its some dude who gets in my face and pushes me I don't think the law would be on my side if my reaction was to draw my M&P and put 3 holes in his chest.

tl;dr
I wouldn't recommend legal advice on JSP btw. Stay safe, dont snap any necks unnecessarily.

You really even need to ask? You live in Canada. You would be charged. The law clearly states you are to be a sissy and run, screaming politically correct statements, then get your feelings checked for free at the hospital. Sorry to say, but you should already know you can't do that. None the less, informed you now are. Good luck!

U.S. and Canada alike, you would be charged; yes. Snapping someone's neck is an overuse of force an near all situations short of someone being murdered and you're saving the day

Where did you get this bullshit information from?

You don't need to give three warnings lol.

Partyplanner, in Canada you will likely face charges unless snapping the assailant's neck was proportionate to the threat they posed. For example if you snapped his neck after he slashed at your neck with a knife, you would probably be fine. Snap his Back after he pocket sands you? Uh oh.