As far as I am concerned, back to back ticketing is IMPOSSIBLE for an airline to prove.
My question is - I am doing back to back ticketing? For example, I am the type that calls airlines, travel agents and looks all over cyberspace before I buy my tickets. Sometimes I have "beat the system" by flying to destination B, then returned to destination A months later. In the meantime, it is cheaper (I saved over $500) to go back to destination A from destination B two or three times. I have saved hundreds of dollars just because I have spent the time to figure out the very complicated fare structure of the airlines. What can the airlines do about this and how would they ever prove it?