Here in Colorado, if someone enters you house to loot it or whatever, assuming you didn't give them permission, there is nothing (legally) to stop you from shooting them dead (from inside you house that is - you would be on shaky ground shooting into your house from your backyard). You may face moral hurdles, but not legal ones. Because of our "Make My Day" law, you will not face criminal or civil charges. This law is not applicable to your backyard, your driveway, etc. Only INSIDE your PRIMARY RESIDENCE.

The important points of the law are that it must be inside your primary residence (not some rental property that you happen to own), the intruder must not have been invited in, and you must perceive some potential for harm. The "potential for harm" can be as minor as "I thought he might bump into me and knock me against the wall". In other words, pretty much anything will qualify as long as you don't say "I perceived absolutely zero threat or potential for harm. None. Nada." It is also acceptable to shoot if the intruder is running away from you down a hall, and your family members happen to be in a room at the end of the hall. There is potential for harm there, and it qualifies. This is per a lawyer who specializes in firearms related self defense here in my state (I attended a seminar he hosted on the topic).

Each state is different though. I think things are a lot different here than they would be if you lived in NY, NJ, CA, IL, D.C., etc.