It all started when Sparty-pants got into a drunken brawl one night and killed two of his fellow centurions with his bare hands. He was immediately summoned before a summary court-martial.
Rome didn’t become an empire by having liberal policies toward criminals. There was no such thing as rehabilitation. You committed a crime and you were history.
Nearly everything could be interpreted as a capital crime. I don’t know if you could be executed for letting out a fart but if I were you, I would try to hold it in, if I was living in 1st century BC Rome……..