Well, you better make sure you have it if you ever intend to use a gun against an intruder breaking into your house at night.

Officer Jarrod Shivers was shot and killed while executing a search warrant in Cheseapeake, Virginia Thursday night. 

The suspect had no criminal record (at least in the state of
Virginia). And he says in an interview from jail he had no idea the
undercover cops breaking into his home were police. The suspect,
28-year-old Ryan David Frederick, also says a burglar had broken into
his home earlier this week.

Thought the raid was apparently part of a drug investigation, police
aren’t saying what if any drugs were found. They won’t even confirm
that police had the correct address. But they have arrested Frederick
and charged him with first-degree murder.

Also a good idea to "have nothing to hide" (uh…, so "you don’t have to worry").

(Balko)

Update

Update II