be under orders

To be following the instructions given by a superior. I'm under orders to detain the suspect until the detective can question him. We're under orders to shoot down any aircraft in the no-fly zone. Look, we're just under orders to bring you in to the station. The Chief will dictate what happens to you next.

be under ˈorders (to do something)

have been ordered or commanded (to do something): Prisoners of war were under orders to reveal only their name, rank and number.