The Federal Employees Pay Act, 5 U.S.C. 5544-45, provides for premium on-call duty pay for “an employee in a position requiring him regularly to remain at, or within the confines of, his station during longer than ordinary periods of duty.”

An employee is on duty, and time spent on standby duty is hours of work if, for work-related reasons, the employee is restricted by official order to a designated post of duty and is assigned to be in a state of readiness to perform work with limitations on the employee’s activities so substantial that the employee cannot use the time effectively for his or her own purposes.

A finding that an employee’s activities are substantially limited may not be based on the fact that an employee is subject to restrictions necessary to ensure that the employee will be able to perform his or her duties and responsibilities, such as restrictions on alcohol consumption or use of certain medications.

An employee is not considered restricted for “work-related reasons” if, for example, the employee remains at the post of duty voluntarily, or if the restriction is a natural result of geographic isolation or the fact that the employee resides on the agency’s premises.