We discussed this at some length in the CCW classes I took, including one with a lawyer ...
He was talking about Colorado, and I thought some of the information was contradictory.
1. You cannot use deadly force to defend property (draw a gun, brandish a gun, threaten with a gun, etc.)
2. You CAN use physical force to defend property (get in some one's way, tackle them, etc.)
Where it gets hard, though ... the lawyer felt that if you were facing a number of people who conceivably could be a threat, it would not be brandishing to draw a weapon and hold it at your side when confronting them; this would simply be taking a reasonable caution when confronting multiple criminals with unknown intent, and under the circumstances not brandishing to the reasonable citizen.
However ... technically if those people laught at you and continue to steal your car (or whatever) at this point there's nothing you can really do besides allow it to happen.
If they all come at you after you confront them, or one displays a weapon (even if he just pretends to have a weapon by reaching under his coat or whatever) ... well, now they've threatened you with deadly force and the situation just changed. Take action to defend yourself as you see fit.
On the other hand ... realistically, if you hold an unarmed BG at gunpoint until the police arrive and he really is a provable criminal, it's highly unlikely (at least in this state) that you'll be criminally prosecuted. The DA's know a jury is unlikely to convict someone who didn't actually shoot anybody, but used a legally owned/possess firearm to confront felons. It's technically illegal, but it's not something you'll generally be prosecuted for.
You takes your chances ...
For me, I probably wouldn't be too confrontational defending my property. But would be HIGHLY aggressive at defending my life.