The Fair Labor Standards Act (FLSA) establishes fair wages and labor standards for employment in the United States. It relates mostly to law enforcement in two main areas, although other areas of concern are covered by the law. First, overtime rules kick in when an employee works more than 40 hours per week which is common in law enforcement. It is connected to the second concern which deals with hours worked.
The number of hours worked for law enforcement can be a difficult issue to narrow down. It is obvious that an officer in a squad car responding to calls is "working". However, FLSA also requires officers who are in court be considered "working". The biggest issue of contention among many officers and their departments revolves around "on call" duty hours. This is time when an officer is not necessarily working, but may be called in to shift at any time and therefore has restrictions on what they can do or how far they can travel from home.
The number of hours worked directly impacts the overtime regulations imposed by the FLSA. Departmental policies can limit overtime by adjusting schedules or providing another compensation up to a certain point. For example, some state police departments will provide Compensation Leave for any hours worked over 40 up to 43 hours. After 43 hours, overtime kicks in.
The reason hours worked is so important in law enforcement is due to the various activities they may be required to do which do not require them to respond to duty calls. An officer may be present at a sporting event for example. They are still required to handle situations there, but not respond to other events. Additionally, training and roll call were events not considered duty time, but FLSA allowed officers to challenge it.