In 1715 he was called to the bar, where his progress was, says Lord Campbell, more rapid than that of any other debutant in the annals of our profession, his advancement being greatly furthered by the patronage of Macclesfield, who became lord chancellor in 1718, when Yorke transferred his practice from the king's bench to the court of chancery, though he continued to go on the western circuit. In the following year he established his reputation as an equity lawyer in a case in which Robert Walpole's family was interested, by an argument displaying profound learning and research concerning the jurisdiction of the chancellor, on lines which he afterwards more fully developed in a celebrated letter to Lord Kames on the distinction between law and equity. Through Macclesfield's influence with the duke of Newcastle Yorke entered parliament in 1719 as member for Lewes, and was appointed solicitor-general, with a knighthood, in 1720, although he was then a barrister of only four years standing.
Although in his youth he contributed to The Spectator (1711) over the signature Philip Homebred, he seems early to have abandoned all care for literature, and he has been reproached by Lord Campbell and others with his neglect of art and letters. He married, on May 16 1719, Margaret, daughter of Charles Cocks (by his wife Mary, sister of Lord Chancellor Somers), and widow of John Lygon, by whom he had five sons and two daughters:
In 1739, he purchased Wimpole Hall, the greatest country house in Cambridgeshire.
Hardwicke was succeeded in the earldom by his eldest son, Philip.
Lord Hardwicke is also remembered as one of the two authors of the Yorke-Talbot slavery opinion whilst he was a crown law officer in 1729. The opinion was sought to determinate the legality of slavery and Hardwicke (then Philip Yorke) and Charles Talbot opined that it was. The opinion was disseminated and relied upon widely. Lord Hardwicke would subsequently endorse the views in the opinion in a judicial capacity in Pearne v Lisle (1749) Amb 75, 27 ER 47.
Hardwicke's political importance was greatly increased by his removal to the House of Lords, where the incompetency of Newcastle threw on the chancellor the duty of defending the measures of the government. He resisted Carteret's motion to reduce the army in 1738, and the resolutions hostile to Spain over the affair of Captain Jenkins's ears. But when Walpole bent before the storm and declared war against Spain, Hardwicke advocated energetic measures for its conduct; and he tried to keep the peace between Newcastle and Walpole. There is no sufficient ground for Horace Walpole's charge that the fall of Sir Robert was brought about by Hardwicke's treachery.
No one was more surprised than himself when he retained the chancellorship in the foilowing administration, and he resisted the proposal to indemnify witnesses against Walpole in one of his finest speeches in May 1742. He exercised a leading influence in the Wilmington Cabinet; and when Wilmington died in August 1743, it was Hardwicke who put forward Henry Pelham for the vacant office against the claims of Pulteney. For many years from this time he was the controlling power in the government.
During the king's absences on the continent Hardwicke was left at the head of the council of regency; it thus fell to him to concert measures for dealing with the Jacobite rising in 1745. He took a just view of the crisis, and his policy for meeting it was on the whole statesmanlike. After Culloden he presided at the trial of the Scottish Jacobite peers, his conduct of which, though judicially impartial, was neither dignified nor generous; and he must be held partly responsible for the unnecessary severity meted out to the rebels, and especially for the cruel, though not illegal, executions on obsolete attainders of Charles Radcliffe and (in 1753) of Archibald Cameron of Locheil. He carried, however, a great reform in 1746, of incalculable benefit to Scotland, which swept away the grave abuses of feudal power surviving in that country in the form of private heritable jurisdictions in the hands of the landed gentry. On the other hand his legislation in 1748 for disarming the Highlanders and prohibiting the use of the tartan in their dress was vexatious without being effective. Hardwicke supported Chesterfield's reform of the calendar in 1751; in 1753 his bill for legalizing the naturalization of Jews in England had to be dropped on account of the popular clamour it excited; but he successfully carried a salutary reform of the marriage law, which became the basis of all subsequent legislation on the subject.
On the death of Pelham in 1754 Hardwicke obtained for Newcastle the post of prime minister, and for reward was created earl of Hardwicke and Viscount Royston; and when in November 1756 the weakness of the ministry and the threatening aspect of foreign affairs compelled Newcastle to resign, Hardwicke retired with him. He played an important and disinterested part in negotiating the coalition between Newcastle and Pitt in 1757, when he accepted a seat in Pitt's cabinet without returning to the woolsack. After the accession of George III Hardwicke opposed the ministry of Lord Bute on the peace with France in 1762, and on the cider tax in the following year. In the Wilkes case Hardwicke condemned general warrants, and also the doctrine that seditious libels published by members of parliament were protected by parliamentary privilege. He died in London on the 6th of March 1764.
Although for a lengthy period Hardwicke was an influential minister, he was not a statesman of the first rank. On the other hand he was one of the greatest judges who ever sat on the English bench. In 1736 the King's Bench, under his presidency, delivered the seminal judgment in Middleton v. Crofts 2 Atk 650, which delivered the national church from the threat of a clerical tyranny by holding that canons made in the provincial clergy convocations could not, by themselves, bind the lay faithful. That decision apart, he did not by his three years tenure of the chief-justiceship of the kings bench leave any impress on the common law; but Lord Campbell pronounces him the most consummate judge who ever sat in the court of chancery, being distinguished not only for his rapid and satisfactory decision of the causes which came before him, but for the profound and enlightened principles which he laid down, and for perfecting English equity into a systematic science. He held the office of lord chancellor longer than any of his predecessors, with a single exception; and the same high authority quoted above asserts that as an equity judge Lord Hardwicke's fame has not been exceeded by that of any man in ancient or modern times. His decisions have been, and ever will continue to be, appealed to as fixing the limits and establishing the principles of the great juridical system called Equity, which now not only in this country and in our colonies, but over the whole extent of the United States of America, regulates property and personal rights more than the ancient common law. Hardwicke had prepared himself for this great and enduring service to English jurisprudence by study of the historical foundations of the chancellors equitable jurisdiction, combined with profound insight into legal principle, and a thorough knowledge of the Roman civil law, the principles of which he scientifically incorporated into his administration of English equity in the absence of precedents bearing on the causes submitted to his judgment. His decisions on particular points in dispute were based on general principles, which were neither so wide as to prove inapplicable to future circumstances, nor too restricted to serve as the foundation for a coherent and scientific system. His recorded judgments which, as Lord Campbell observes, certainly do come up to every idea we can form of judicial excellence combine luminous method of arrangement, with elegance and lucidity of language.
The contemporary authorities for the life of Lord Chancellor Hardwicke are voluminous, being contained in the memoirs of, the period and in numerous collections of correspondence in the British Museum. See, especially, the Hardwicke Papers; the Stowe manuscripts; Hist. manuscripts Commission (Reports 2, 3, 4, 6, 8, 9, 11); Horace Walpole, Letters (ed. by P Cunningham, 9 vols., London, 1857-1859); Letters to Sir H Mann (ed. by Lord Dover, 4 vols., London, 1843 1844), Memoirs of the Reign of George II (ed. by Lord Holland, 2nd ed. revised, London, 1847); Memoirs of the Reign of George III (ed. by GFR Barker, 4 vols., London, 1894); Catalogue of Royal and Noble Authors of England, Scotland and Ireland (ed. by T Park, 5 vols., London, 1806).
Horace Walpole was violently hostile to Hardwicke, and his criticism, therefore, must be taken with extreme reserve. See also the earl Waldegrave, Memoirs 1754-1758 (London, 1821); Lord Chesterfield, Letter (ccl. by Lord Mahon, 5 vols., London, 1892); Richard Cooksey, Essay on John, Lord Somers, and Philip, Earl of Hardwicke (Worcester, 1791); William Coxe, Memoirs of Sir R. Walpole (4 vols., London, 1816); Memoirs of the Administration of Henry Pelham (2 vols., London, 1829); Lord Campbell, Lives of the Lord Chancellors, vol. v. (8 vols,, London, 1845); Edward Foss, The Judges of England, vols. vii. and viii. (9 vols., London, 1848-1864); George Harris, Life of Lord Chancellor Hardwicke; with Selections from his Correspondence, Diaries, Speeches and Judgments (3 vols., London, 1847).