This article focuses on the Irish-born metropolitan radical and parliamentary journalist Peter Finnerty, exploring, in particular, the distinctive nature of his political engagement. Chiefly remembered as a friend of William Hazlitt and an implacable opponent of Lord Castlereagh, Finnerty was an influential figure in his own right, who moved between a range of social and political spaces. Framing him as an unrepentant Irish radical, indifferent to the coercive power of authority, this article will examine Finnerty's involvement in a range of scandals, controversies, and causes célèbres, and will highlight the ways in which he succeeded, through enacting a contempt for authority, in subverting both the courtroom and Parliament itself.