Political violence provides many challenges for the public law of a constitutional democracy, putting assumptions about the rule of law and civil liberties under sometimes immense strain. This has been the case in the United Kingdom for many years (as a result of IRA-related violence) but has become prevalent across the democratic world following the emergence during the 1990s of political violence purportedly rooted in the Islamic faith. The pivotal events were of course those of 11 September 2001, with the range of global anti-terrorism laws that these provoked. The Hamas actions of 7 October 2023 in Israel, and in particular the response to these by Israel, suggest that further terrorist violence is to be expected in Europe and further afield. The security group engages with the range of laws generated by domestic and cross-border political violence, seeking to analyse their place in public law and their implications for civil liberties and human rights. It also takes a long view on such laws, seeking to place them in their historical context. The interaction between anti-terrorism law and human rights norms (for example in the UK the Human Rights Act) is also the subject of close study, as are the theoretical underpinnings of liberty and security in constitutional democracies. The diverse specialisms of public law scholars at LSE enables a strong and well-informed comparative aspect to the work of the sub-group.