Introduction Designating and outlawing enemies of the state – the act of proscription – has a long and ignoble political history that stretches back to the industrious empirebuilding of pre-Christendom Rome. In 82 bc Lucius Cornelius Sulla published lists of those he considered enemies of the state, stripping them of their Roman citizenship, confiscating their wealth, and sanctioning their extrajudicial killing. Cicero, the classical philosopher and statesman was killed under such an order at Sulla’s command. Similar proscriptions, under the rubric of ‘outlawry’, were apparent in Britain a millennium later. Before the Magna Carta was signed by King John in 1215, the British sovereign could outlaw foes with the declaration of caput lupinum: literally, ‘May his be a wolf ’s head’. As with Sulla’s proscriptions, a declaration of caput lupinum withdrew state protections from the unfortunate subject, placing him or her on an equal footing with wild animals and thus likewise be killed as such. These are more than interesting historical footnotes. Today, variations of Sulla’s proscription have been used energetically in pursuit of today’s class of (those designated) terrorist. The powers to outlaw organisations and target extremists employed in Australia, Canada, the UK, US and elsewhere bear a striking resemblance to Sulla’s proscriptions. Powers to strip citizenship are already partly in place; the confiscation of wealth is lawful in all Anglosphere states; and extrajudicial killing via drones in the Middle East, North Africa and South Asia is a routine feature of the worldwide campaign by US, UK and allied countries’ campaign against Islamic extremism. Since the beginning of the millennium, the upsurge in international terrorism has propelled a radical global revision of anti-terrorism laws, in which proscription plays a central role, funnelling decision-making powers upwards into the hands of the executive and away from the legislature and the judiciary. This is a feature common to the four countries considered in this chapter: Australia, Canada, the UK and US. Referred to here as Anglosphere states (Bennett 2004, 2007), they share a political, legal and institutional framework built on common law principles, a shared language and a commitment to liberal democratic ideas stemming from the Westminster style of government.