It's actually a majority of states (31) now. These laws don't simply mean you can shoot anyone who trespasses in your house; the entry must be forceful and you

It's actually a majority of states (31) now. These laws don't simply mean you can shoot anyone who trespasses in your house; the entry must be forceful and you must believe that the person intended to seriously harm someone in the house or remove someone against their will. The castle doctrine simply creates a presumption that, barring evidence to the contrary, someone who "unlawfully and forcibly" enters a home plans to harm the people inside.