Biofuel policy has become highly contentious in Europe. In this paper we discuss the governance and legitimacy aspects of the carbon and sustainability system of the UK Renewable Transport Fuel Obligation (RTFO), both before and after implementation of the Renewable Energy Directive. RTFO certification is of a meta-type, being built upon existing certification and labelling schemes, each of which are more or less contested by NGOs. Despite the RTFO being based on these non-state initiatives, so far the concerns of environment and development NGOs and others have not been given serious expression in regulatory terms. Indeed, biofuel policy development in the UK has arguably been unduly non-responsive to critical opinion, given the limited scientific base on biofuel impacts and the reliance of RTFO sustainability certification on non-state actors and schemes. Drawing on documentary evidence, interviews and three sets of literatures - co-production of regulation; post-normal science; and legitimacy of non-state certification and labelling processes - we suggest that until concerned voices are given a stronger expression in UK and EC biofuel policy development, the policy cannot yet be said to have achieved a wide social mandate. (C) 2011 Elsevier Ltd. All rights reserved.