Chapter 4 begins the book’s analysis of British parliamentary debates by outlining the diverse ways in which the power of proscription is positioned politically and normatively therein. The chapter demonstrates that proscription is consistently depicted as a power of significance that merits a certain seriousness. For proscription’s advocates, this significance comes from its contribution to national security via the prevention, deterrence and disruption of terrorist ambitions, as well as its symbolic value in communicating British or parliamentary resolve to would-be terrorists. Parliamentary critics of proscription, on the other hand, see the power as important, we argue, because of its deleterious implications for social and political life within Britain. These include issues around its effectiveness; its potentially counter-productive implications; the civil liberty consequences of listing organisations; and the impact of proscription upon democratic processes more broadly. In reflecting on these arguments, the chapter highlights some of the rhetorical strategies upon which politicians draw within these debates, as well as a tendency – not uncommon – for distraction and diversion therein.