The theme would be law and punishment as it shows that you get punished for what you do. However there is a twist to the plot, where in fact the criminal helps out the hitchhiker and prevents him for being punished, but this is bad as they are not being punished for what they did wrong. Also another theme could be based around the idea of ‘if I scratch your back, you scratch mine’, meaning that the man helped the hitchhiker out by offering him a lift instead of driving past like every other person, and in the end the hitchhiker repays him by preventing him from getting a ticket.