A technique to enforce a physical security constraint leverages a user's mobile device while at the same time enabling the user to continue use of the device for appropriate purposes within a restricted area. A user's access to a restricted area with his or her mobile device in effect is “conditioned” upon installation (on the device) of an endpoint agent that controls features of the mobile device based on one or more factors, such as the user's role, a current location of the user within the restricted area, and other criteria as defined in a security policy. Preferably, the agent is instantiated automatically when the user enters the restricted area, with the device then restored to its prior state when the user leaves the restricted area. The particular features of the mobile device that are controlled may be varied, even within particular zones of the restricted area itself.