An employer can require an employee to be on call.
The U.S. Department of Labor has laid out the following general rules regarding on/off duty time and on-call time:
- Employees who are temporarily idle while waiting for further work in such a way that they are not able to use the time effectively for their own purposes must still be regarded as working, according to 29 C.F.R. 785.15. Periods during which an employee is completely relieved from duty and which are long enough to enable him to use the time effectively for his own purposes are not hours worked. He is not completely relieved from duty and cannot use the time effectively for his own purposes unless he is definitely told in advance that he may leave the job and that he will not have to commence work until a definitely specified hour has arrived. Whether the time is long enough to enable him to use the time effectively for his own purposes depends upon all of the facts and circumstances of the case. 29 C.F.R. 785.16.
- An employee who is required to remain on call on the employer's premises or so close thereto that he cannot use the time effectively for his own purposes is working while “on call”. An employee who is not required to remain on the employer's premises but is merely required to leave word at his home or with company officials where he may be reached is not working while on call. 29 C.F.R. 785.17.
If an employee is required to perform work while on call, this time would be considered compensable time and it is possible that the employee would be entitled to additional pay for this time unless the employee is salaried exempt under the Fair Labor Standards Act (FLSA).