Yes, your employer can require that you remain on the premises during your meal period, even if you are relieved of all work duties.
However if this occurs, you are being denied your time for your own purposes and your remain under the employer’s control and thus, the meal period must be paid.
Also, keep in mind that there are minor exceptions to this general rule for healthcare workers. According to Industrial Welfare Commission Wage Orders, if you are required to eat on the premises, a suitable place for that purpose must be designated.
“Suitable” means a sheltered place with facilities available for having hot food and drink or for heating food or drink, and for consuming such food and drink.
David Payab, Esq. from The Law Offices of Payab & Associates can be reached @ (818) 918-5522 or by visiting http://payablaw.com/