Joe Went to Sam the Barber for a Haircut

Joe went to Sam the barber for a haircut.When Sam finished,Joe looked in the mirror and was horrified; he refused to pay and got up to leave.Sam refused to let him go,this being the third customer that day who had tried to leave without paying.Sam insisted that Joe stay while he phoned the police.Joe did so.When the police arrived and Sam explained the situation to them,the police told him that they wouldn't arrest Joe,and that Sam would have to pursue other remedies.Joe later sued Sam for false imprisonment.Explain the likely outcome.