Victoria Gillick challenged guidance issued by the Department of Health and Social Security, which advised that in exceptional circumstances a doctor may prescribe contraception to a girl under 16 without her parents' knowledge or consent. This chapter outlines the decision of their Lordships in Gillick. It argues that some of the difficulties presented by Gillick stemmed from the lack of precedent on the test for capacity applicable to adults, and there is now a pressing need to reconcile the child test with the adult test. The chapter analyses the treatment decisions of mature children using the Principle of Generic Consistency (PGC). It addresses a preliminary terminological issue with regard to the use of 'competence' and 'capacity'. According to Christman, what makes 'a conception of autonomy uniquely "relational" or "social" is that among its defining conditions are requirements concerning the interpersonal or social environment of the agent'.