台灣人都堡壘原則都有普遍的誤解，以為入侵就可以擊斃。堡壘原則只保障你可以用致命武器防衛，並沒有讓你可以隨意殺人。（以台灣人的觀點，入侵就是殺，這是錯的）
堡壘原則各州都有不同的限制，在美國也常在討論。
很多人都會拿幾個案例來說，但一兩個案例，並不代表就適用美國每個州，再者有些案例本身也有爭議。例如老夫婦射殺日本人案，很多人質疑因為死的是日本人，陪審團才會判兇手無罪，如果是白人，相信判決會不同。
以加州為例，你要合理射殺入侵者，必須舉證對方有嚴重暴力行為，足以對你或家人人身造成嚴重傷害。以本案來說，顯然不成立。
再者一槍打死人是一回事，你把人打到無行為能力，再繼續打死他，在美國恐怕也很難擺脫刑事責任。
參考以下連結：
http://www.calguns.net/calgunforum/...ad.php?t=449181
No, the California Castle Doctrine doesn't give you the benefit of the doubt. Characterizing it thus is woefully imprecise and misleading. "Benefit of the doubt" is not a legal concept and not the way things will work.
[1] Self defense is an affirmative defense. If you shoot someone you have committed, prima facie, the elements of a crime. Your defense is that you shot in self defense thus legally justifying your act of violence. But it's your burden to put forth evidence establishing the you met the legal standard justifying your act.
[2] In California, Penal Code 197 describes the legal standard that must be met to justify a your committing a homicide:
"197. Homicide is also justifiable when committed by any person in any of the following cases:
1. When resisting any attempt to murder any person, or to commit a felony, or to do some great bodily injury upon any person; or,
2. When committed in defense of habitation, property, or person, against one who manifestly intends or endeavors, by violence or surprise, to commit a felony, or against one who manifestly intends and endeavors, in a violent, riotous or tumultuous manner, to enter the habitation of another for the purpose of offering violence to any person therein; or,
3. When committed in the lawful defense of such person, or of a wife or husband, parent, child, master, mistress, or servant of such person, when there is reasonable ground to apprehend a design to commit a felony or to do some great bodily injury, ..."
[3] So in order to establish that shooting the guy in your home was justified you will have to demonstrate that the requirements of Penal Code 197 were satisfied. Penal Code 198.5, California's Castle Doctrine, creates a presumption that can make it easier for you to establish, as your affirmative defense, that your act of violence was justified.
[4] A presumption is a rule that affects evidence and burden of proof in court. Ordinarily, one who asserts something in court will have the burden of proving, by presenting good evidence, that certain facts supporting that assertion are true. But sometimes the law might allow one of those facts to be accepted as true without specific evidence of that fact if the party with the burden of proof shows that certain other facts are true. So the party might be entitled under a rule of law to have fact A presumed to be true if facts B, C, and D are shown to be true, even if the party produces no direct evidence that fact A is true.
[5] So with the presumption of Penal Code 198.5, you would not have to show specifically that you, "...held a reasonable fear of imminent peril of death or great bodily injury to self, family, or a member of the household..." if you can show both that (1) the person you shot "...unlawfully and forcibly enters or has unlawfully and forcibly entered the residence...."; and (2) you "...knew or had reason to believe that an unlawful and forcible entry occurred...."
[6] But note that any legally available presumption is rebuttable. That means that even though one may be entitled to the benefit of a presumption as to a certain fact, the other side may try to prove that fact is not actually true. So, for example, even if you might have been entitled to a presumption that you were reasonably in fear for your life, the prosecutor could put on evidence and try to show that under the particular circumstances, a reasonable person could not have been reasonably in fear for his life.