In order to explain how independent assessment of the current balance between counter-terrorism legislation and civil liberties is addressed in the UK, the paper sets the scene of how various mechanisms pursue this undertaking. However, the focus turns to the Independent Reviewer of Terrorism Legislation, an office formalised in 2001 as the prime device for scrutiny. The text analyses the nature and history of the office, including remit, resources, and powers. There follows a critical assessment of performance. It is examined in terms of outputs, independence, the varied impacts of significant initiatives, and relations with executive, legislature, and judiciary. The notion of an independent expert assessor is found to add value to the other devices of accountability. The office asserts good governance by which the values of the rule of law and rights observance are to be secured and so has the potential to augment the legitimacy of counter-terrorism in the United Kingdom.