I saw this week a flight out of Scotland was canceled as one of the pilots were arrested. No mention of whether it was the CA or FO but doesnt matter. Question.. what options do one or the other crew members have if they are aware.... Suppose the offender doesnt take a suggestion to call out sick. What if the other refuses the flight at that point? How about another crew member ? Is it if they show up at the airport or whenever they cross the threshold that is the point of no return.