This article reviews the basic elements in John Stuart thought on freedom of expression, public opinion and the role of journalism in a democratic society, ideas bringing together and con- solidating a tradition which began in the seventeenth century and continues through to the present day. It also considers Mill’s thought in relation with the views of thinkers who came before him, Milton and Jefferson, for example, and his contemporary, Tocqueville. Among the core ideas in Mill’s writings are the “harm principle”, his ap- proximation to the idea of truth, and his account of how political debate should be carried out. His extensive body of work has given rise to intense debate which is still lively today. As Isaiah Berlin emphasised, “[...] the critics of Mill have, on the whole, exceeded the number of his defenders. Nevertheless, the inner citadel – the central thesis – has stood the test”