if YOU are threatened, not your property.
tazer's are illegal.
self-defence is not a complete defence, only partial. meaning: you kill someone you don't get done for murder, but manslaughter. up to the judge whether he believes you or not. you may even get off.
however, doesn't automatically mean you are free from liability...
a judge will always frown upon you 'defending' your property, such as a car, rather than your 'persons,' as property can always be replaced and its not a danger to yourself.