George Villiers, 2nd Duke of Buckingham befriended him, and he was knighted and made a King's Counsel in 1671.
He directed the prosecution of the victims of Titus Oates's plot in 1678, but resigned from the attorney-generalship in November 1679, saying that he had found the burden of work intolerable.
As a man noted for his timid disposition, he was probably not well suited to be a law officer in a time of acute political crisis.
He was a manager for the Commons at Lord Stafford's trial (30 November), where he presented the prosecution case with skill, and was heavily involved in the passage of the Exclusion Bill through the Commons: his forceful speeches attracted much attention, and were notable contrast to his normal reputation for timidity.
He was satirised by the court wits, and John Dryden introduced him as 'Bull-faced Jonas' into Absalom and Achitophel (1681).