His influence in the city of London, where opposition to the government of Charles II. was now becoming pronounced, enabled Jeffreys to make himself useful to Danby. In September 1677 he received a knighthood, and his growing favour with the court was further marked by his appointment as solicitor-general to James, duke of York; while the city showed its continued confidence in him by electing him to the post of recorder in October 1678. In the previous month Titus Oates had made his first revelations of the alleged popish plot, and from this time forward Jeffreys was prominently identified, either as advocate or judge, with the memorable state trials by which the political conflict between the Crown and the people was waged during the remainder of the 17th century. The popish plot, followed by the growing agitation for the exclusion of the duke of York from the succession, widened the breach between the city and the court. Jeffreys threw in his lot with the latter, displaying his zeal by initiating the movement of the "abhorrers" (q.v.) against the "petitioners" who were giving voice to the popular demand for the summoning of parliament. He was rewarded with the coveted office of chief justice of Chester on the 30th of April 1680; but when parliament met in October the House of Commons passed a hostile resolution which induced him to resign his recordership, a piece of pusillanimity that drew from the king the remark that Jeffreys was "not parliament-proof." Jeffreys nevertheless received from the city aldermen a substantial token of appreciation for his past services. In 1681 he was created a baronet. In June 1683 the first of the Rye House conspirators were brought to trial. Jeffreys was briefed for the crown in the prosecution of Lord William Howard; and, having been raised to the bench as lord chief justice of the king's bench in September, he presided at the trials of Algernon Sidney in November 1683 and of Sir Thomas Armstrong in the following June. In the autumn of 1684 Jeffreys, who had been active in procuring the surrender of municipal charters to the crown, was called to the cabinet, having previously been sworn of the privy council. In May 1685 he had the satisfaction of passing sentence on Titus Oates for perjury in the plot trials; and about the same time James II. rewarded his zeal with a peerage as Baron Jeffreys of Wem, an honour never before conferred on a chief justice during his tenure of office. Jeffreys had for some time been suffering from stone, which aggravated the irritability of his naturally violent temper; and the malady probably was in some degree the cause of the unmeasured fury he displayed at the trial of Richard Baxter (q.v.) for seditious libel--if the unofficial _ex parte_ report of the trial, which alone exists, is to be accepted as trustworthy.