The security of states - and of the communities and individuals within them - has long raised profound challenges for the Rule of Law.Protecting against threats of terrorism and other serious crimes can require state agencies to act in ways that infringe liberties, often covertly. At the same time, living securely demands that the scope and limits of state powers are appropriate and respect rights, that institutions and agencies of the state are accountable and transparent. The Rule of Law requires the Government to hold to certain minimum standards, even when it is upholding national security by countering attacks on democracy. Compliance with the Rule of Law is a prerequisite to maintaining international peace and security. In this programme of work, we investigate how to ensure that states perform their duty to ensure security in a way which respects the Rule of Law, including international law, and how to ensure that international legal frameworks keep up with technological developments in the means available to States to protect security.