The evaluation of technologies and their risks is a hybrid exercise, involving the forging of facts and proofs of the properties of these technologies, and judgment calls about the value of these technologies and underlying risks for society. This regulatory science, where the construction of facts about technologies mix with debated legal, social and economic criteria of technological desirability, is a particularly challenging area for scientists to navigate and gain authority in. This is all the more the case now as the practices and norms of regulatory science appear to be influenced by the very industries it helps to regulate. This chapter discusses how expert objectivity and authority have historically been negotiated in regulatory science and the associated changes in a context that is politicized by claims of industry capture and scientists’ conflicts of interest. It argues that the authority of experts and their reputation for objectivity and responsibility have much to do with their positions in various fields—administrative, industrial, academic, and social mobilization—that is, in the broad ecology in which regulatory knowledge contentiously takes form.