MANSFIELD, WILLIAM MURRAY, 1ST EARL OF (1705-1793), English judge, was born at Scone in Perthshire, on March 2, 1705, the son of the 5th Viscount Stormont. He was educated at Perth grammar school, Westminster School and Christ Church, Oxford. He was called to the bar at Lincoln's Inn in 1730. He was a good scholar and mixed with the best literary society, being an intimate friend of Alexander Pope. His ap pearance in some important Scottish appeal cases brought him into notice, and in Scotland at least he acquired an immense repu tation by his appearance for the city of Edinburgh when it was threatened with disfranchisement for the affair of the Porteous mob. His English practice had as yet been scanty, but in 1737 a single speech in a jury trial of note placed him at the head of the bar, and from this time he had all he could attend to. In 1738 he married Lady Elizabeth Finch, daughter of the earl of Win chelsea. In 1742 he was appointed solicitor-general.
During the next 14 years Mansfield was one of the most con spicuous figures in the parliamentary history of the time. By birth a Jacobite, by association a Tory, he was nevertheless a Moderate. In the year 1754 he became attorney-general, and for the next two years acted as leader of the House of Commons under the administration of the duke of Newcastle. But in 1756, a vacancy occurred in the chief justiceship of the king's bench, and he claimed the office, being at the same time raised to the peerage as Baron Mansfield.
From this time the chief interest of his career lies in his judicial work, but he did not wholly dissever himself from politics. He became by a singular arrangement, only repeated in the case of Lord Ellenborough, a member of the cabinet, and remained in that position through various changes of administration for nearly fifteen years, and, although he persistently refused the chancellor ship, he acted as Speaker of the House of Lords while the Great Seal was in commission. During the time of Pitt's ascendancy he took but little part in politics, but while Lord Bute was in power his influence was very considerable, and seems mostly to have been exerted in favour of a more moderate line of policy. He was a
supporter of the prerogative. In 1776 he was created earl of Mansfield. In 1783, although he declined to re-enter the cabinet, he acted as Speaker of the House of Lords during the coalition ministry, and with this his political career may be said to have closed. He continued to act as chief justice until his resignation in June 1788, and died on March 20, 1793.
It is as a judge, however, that Mansfield is chiefly remembered. In the sphere of commercial law he stands alone as having reduced it almost to an exact science, where before it was a chaos of unselected decisions. And the same may be said of the doctrine of quasi-contract, where he found the law again in a chaotic state just fitted for his systematising genius, and left it a coherent body of rules founded on the principle of unjust enrichment. (See Moses v. Macfarland, 2 Burr. 1005.) But when he had to deal with a body of law already elaborately worked out with settled principles, he went wrong. Thus his attempts to "rationalise by a side wind" our law of seisin (Taylor and Atkyns v. Horde, I Burr. 113), and to anticipate the Judicative Act by allowing a plaintiff to set up an equitable title, was bound to fail, as was his more ambitious and very nearly successful attempt to revolutionise the doctrine of consideration by basing contract on moral obligation and reducing consideration to credentiary value only (Pillans v. Van Mierop, 3 Burr. 1663). But while his wide acquaintance with continental jurisprudence sometimes led him astray in matters dependent exclusively on English Common Law the trend of legislation in the 19th century has often followed the lines he tried to lay down.