UK climate change policy is based on the advice of the Committee on Climate Change established under the Climate Change Act 2008. This Committee is an independent, expert agency established as part of the reconceiving of the regulatory state as a response to the neo-liberal critique of older forms of regulation. But the quality of the advice given in the Committee’s recent Fourth Carbon Budget Review is so tendentious as to barely be able to be described as advice at all. This grave shortcoming poses the most serious questions for contemporary constitutional and regulatory processes.