Abstract
Security policy specification can be difficult to get right. Electronic systems often fail to provide an easy route to encode requirements that would be simple to enforce through controlling how physical principals interact. This paper presents a means to ameliorate potential policy mismatches through the use of location awareness systems allowing changes in the physical world to be mapped to electronic policy state. These changes are represented formally using the event calculus. Patterns over this state are used to track compliance with policy and to detect the fulfilment of obligations. A number of example scenarios are provided to illustrate the utility of the coupling between spatial and policy concerns, and to demonstrate the notation used.