Yes, employees who work in excess of 40 hours per week must be paid overtime at time and a half. However, if the boss sets a policy that you are not supposed to work beyond a certain time, you can be disciplined. The law that covers this is the Fair Labor Standards Act. It is not designed to punish those who have employees who try to abuse the system by collecting overtime when they are not supposed to. If the boss ignores the fact that some people work late, the boss must still pay the overtime, but does not have to allow persistent abuse.