At least in the US your laws clearly start with those freedoms. In Canada the law about such things is so vague and muddy that no two people, experts, cops, or judges seem to agree on what is legal and what isn't.

If you read the law and just interpret the words, everybody would go to jail for shooting another man unless he could prove his life would end if he didn't...regardless of home invasion or any other situational differences.

Perception and reality are completely different. A cop once told me that as long as you don't shoot somebody in the back and you make sure you KILL him and do it ON your property, you'll get off unless your lawyer is completely incompetant regardless of the actual situation.