This article argues that there is a need to modernise the law governing accountability of the UK security and intelligence agencies following changes in their work in the last decade. Since 9/11 the agencies have come increasingly into the spotlight, especially because of the adoption of controversial counter-terrorism policies by the government (in particular forms of executive detention) and by its international partners, notably the US. The article discusses the options for reform in three specific areas: the use in legal proceedings of evidence obtained by interception of communications, with regard to the increased importance and scle of collaboration with overseas agencies, and to safeguard the political independence of the agencies in the light of their substantially higher public profile. In each it is argued that protection of human rights and the need for public accountability requires a new balance to be struck with the imperatives of national security.