Somewhat tangential on living vs. not living in a country of vigilante justice, I recommend Peter Ustinov's Krumnagel.



A BIT OF SPOILER




The thing begins like this: an American cop sees a guy bursting out of a jewelry shop. Thinking 'robery' he shoots him. Turns out the guy was catching the bus after buying engagement rings. The cop is publicly reprimanded, but privatelly the boss lets him know he did the right thing. A bit later, on a trip to England, the cop essentially repeats the performance and gets a life sentence.... It gets even better