--- - |2 Abstract A case study in the sociology of ideas, this article refines the theory of ‘discursive opportunities’ to examine how intellectual claims cross national and linguistic boundaries to achieve public prominence despite lacking academic credibility. Theories of ‘brainwashing’ and ‘mind control’ originally began in the United States in the 1960s as a response to the growth of new religious movements. Decades later in Japan, claims that so‐called ‘cults’ ‘brainwashed’ or ‘mind controlled’ their followers became prominent after March 1995, when new religion Aum Shinrikyō gassed the Tokyo subway using sarin, killing thirteen. Since then, brainwashing/mind control have both remained central in public discourse surrounding the ‘Aum Affair’ despite their disputed status within academic discourse. This article advances two arguments. Firstly, the transnational diffusion of brainwashing/mind control from the US to Japan occurred as a direct result of the 1995 Tokyo sarin attack, which acted as a ‘discursive opportunity’ for activists to successfully disseminate the theories in public debate. Secondly, brainwashing/mind control became successful in Japanese public discourse primarily for their normative content, as the theories identified ‘brainwashing/mind controlling cults’ as evil, violent and profane threats to civil society. - 'The British Journal of Sociology, EarlyView. '