In the present digital world, we depend on information technology more than ever. Our economy, health, well-being and even our lives depend on it. Information security is a basic requirement, with access control playing a key role in limiting potential risks. However, the digital environment is no longer limited to data, access to the IoT space must also be handled properly.Logic has shown to be very useful in access control. It has been used to formally explain and verify access control policies. Here, logic is employed as a reasoning service in support of other systems. However, a general access control mechanism for logic programs is not available.This paper presents a structural approach that brings Access Control to Logic Programming. It allows to constrain access to the knowledge base, supporting the use of impure predicates, preventing unauthorized side effects (i.e. controlling IoT devices) taking place.