This chapter traces the historical roots of various powers which have facilitated the designation and/or exclusion of specific enemies of the state or society. This is a partly genealogical exercise in which we return to the murky origins of outlawry on the British Isles, and reflect on proscription's gradual displacement of such powers as the principal means of political exclusion. The chapter begins by exploring the importance of outlawry to early medieval society as an instrument of social control, criminal justice and monarchical power, before showing how proscription is woven throughout Parliament’s history as a means of consolidating authority: first, in the proscription of Royalists and Jacobites and then later in the prohibitions of political reformist groups in the eighteenth and nineteenth centuries. The chapter then turns to twentieth-century expressions of proscription: first, as a means of control employed by colonial authorities; second, in response to the spectre of fascism in the 1930s and 1940s; and, third, as a precursor and reaction to the maelstrom of violence throughout the Northern Ireland conflict. The chapter ends by reflecting on the contemporary deployment of proscription under the regime introduced through the Terrorism Act 2000. Here we explore today’s proscription powers, the process of their enactment, and the manner in which proscription has unfolded since 2000. We conclude by sketching the core principles of political exclusion as these have evolved through the British state’s encounters with diverse political foes over the centuries.