However, that's exactly the way Ron Paul proposes to fight the war on terrorists.
Letters or marque are a little different, because your citizens are largely going to be hunting non-citizens. Though there are a lot of similarities. I’m not saying it’s a bad thing, but it is kind of weird for a basically unlicensed untrained person (some states have serious licensing requirements for bounty hunters, most don’t) to be empowered to go get somebody and haul them to court with no real paperwork or extradition or anything.