Since more and more states are passing laws shielding those who use lethal force in justified self defense situations from civil liability, that's less of a concern (of course you need to know the laws in your neck of the woods). Such a sign could, however, effect the opinion of the Grand Jury against you if it was a close call.I think your biggest worry would be what the plaintiff's attorney would do with that sign in a civil suit if you did have to shoot an intruder. Can you imagine that sign and your house on the local TV news?
Frankly the biggest concern would be the fact that putting up one of the more colorfully worded signs would tend to make one look like an idiot.
Since more and more states are passing laws shielding those who use lethal force in justified self defense situations from civil liability, that's less of a concern (of course you need to know the laws in your neck of the woods). Such a sign could, however, effect the opinion of the Grand Jury against you if it was a close call.