Abstract

The protection of personal health information has become a live issue in a number of countries, including the USA, Canada, Britain and Germany. The debate has shown that there is widespread confusion about what should be protected, and why. Designers of military and banking systems can refer to Bell & LaPadula (1973) and Clark & Wilson (1987) respectively, but there is no comparable security policy model that spells out clear and concise access rules for clinical information systems. In this article, we present just such a model. It was commissioned by doctors and is driven by medical ethics; it is informed by the actual threats to privacy, and reflects current best clinical practice. Its effect is to restrict both the number of users who can access any record and the maximum number of records accessed by any user. This entails controlling information flows across rather than down and enforcing a strong notification property. We discuss its relationship with existing security policy models, and its possible use in other applications where information exposure must be localised; these range from private banking to the management of intelligence data.