This paper looks at the dilemmas posed by ‘expertise’ in high-technology regula- tion by examining the US Federal Aviation Administration’s ‘type- certification’ process, through which they evaluate new designs of civil aircraft. It observes that the FAA delegate a large amount of this work to the manufacturers themselves, and discusses why they do this by invoking arguments from the soci- ology of science and technology. It suggests that – contrary to popular portrayal – regulators of high technologies face an inevitable (...) epistemic barrier when making technological assessments, which forces them to delegate technical questions to people with more tacit knowledge, and hence to ‘regulate’ at a distance by evalu- ating ‘trust’ rather than ‘technology’. It then unravels some of the implications of this and its relation to our theories of regulation and ‘regulatory capture’. (shrink)