1794 - counsel for people campaigning for parliamentary reform; Erskine and Vicary Gibbs were assigned as counsel to seven radicals imprisoned and charged with a variety of offences amounting to high treason during the time of William Pitt's goverment; treason trials began at the Old Bailey with the trial of Thomas Hardy, a shoemaker and secretary of the London Corresponding Society; jury returned a verdict of not guilty and Erskine was hailed as a hero by the crowds outside; the government persisted with the trials of John Horne Tooke and John Thelwall and they too, defended by Erskine and Vicary Gibbs, were acquitted and then the prosecution was halted;

1806-1807 - served as Lord Chancellor of the United Kingdom in the Ministry of All the Talents.