The Human Rights Act incorporates Article 9 of the European Convention of Human Rights guaranteeing the right to freedom of thought. Yet, in the absence of any guidance from the European Court of Human Rights and in line with the UK’s legal traditions, the right is protected in a piecemeal fashion akin to liberty and non-interference rather than the positive obligatory rights-based approach. As such, this chapter considers whether the right to freedom of thought exists in the common law. Finding that it does exist but that there is no certainty on its content, scope, or application, it is argued that this does not prevent the courts from determining the right under the common law. Attention is given to legal jurists and philosophers, as well as certain historical developments, which have influenced the UK’s development and protection of the right. The right to freedom of thought, like speech, is the liberty to speak truth to power, to dissent, and to organise an alternative form of governance. Contemporary legislation appears to acknowledge the forum internum (the inner realm of the mind) as a subject necessitating protection, albeit, not under the label of human rights.