This paper proposes the concept of a ‘hybrid institution’, defined with reference to certain institutions within the UK's constitutional order which provide oversight of national security processes. It focuses in particular on the Commissioners who have overseen and oversee the use of investigatory powers and the work of the intelligence services. These institutions, as was once said of another hybrid institution – the Independent Reviewer of Terrorism Legislation – are designed in order to operate within situations in which ‘potential conflicts between state power and civil liberties are acute, but information is tightly rationed’. They are ‘hybrid’ institutions in that they marry certain of the features characteristic of political institutions with others characteristic of legal institutions. The paper considers the relevant institutions and the role they play within the national security constitution, showing how their hybrid status facilitates the performance of a function which neither fully legal nor fully political institutions could fulfil.
