[1] On 25 November 1679 he defended Thomas Knox, accused of libel against Titus Oates, and on 2 July 1680 prosecuted Henry Care for publishing Roman Catholic works.
These marked him as a member of the Tory political faction, which was in power at the time; he was rewarded with a knighthood in 1680 and promotion to King's Counsel.
Wythens oversaw the prosecution of the Rye House Plotters and the conviction of Titus Oates for perjury before travelling to the West Counties following the Monmouth Rebellion.
[2] John Evelyn in 1683 recorded his shock at Wythens' drunken and riotous behaviour just days after he sat on the court which condemned Algernon Sidney to death for treason.
He was dismissed as a Justice on 21 April 1687, apparently for refusing to institute martial law in peacetime; he was replaced by Richard Allibond.