Stop sign

A guy is driving, comes up to a four way stop. He slows down, looks down each street quickly and goes through the sign. A few moments later a police officer pulls him over.
The officer approaches the driver, asks "do you know why I pulled you over?".
The driver sighs, "yes, it's because I slowed down instead of stopping at the stop sign... But what's the difference ?".
The officer asks him to step out of the car, the man complies. The officer then takes out his night stick and starts rapidly beating the man over the head!
After a few hits the officer says "Do you want me to stop, or slow down?"