XCF267402 Portrait of William Murray (1705-93), 1st Earl of Mansfield, 1782-83 (oil on canvas) by Copley, John Singleton (1738-1815); 227.6x144 cm; National Portrait Gallery, London, UK; (add.info.: Barrister of Lincoln\'s Inn 1730; M.P for Boroughbridge 1742; Attorney General 1754; Sergeant at Law 1756; Privy Councillor 1756; Lord Chief Justice 1756-88; Reformer of the way the law and courts worked. Mansfield is best known for his judgment in Somersett\'s Case on the legality of keeping slaves in England. On behalf of Somersett, it was argued that while colonial laws might permit slavery, neither the common law of England, nor any law made by Parliament recognised the existence of slavery, and slavery was therefore illegal. "the legal genius of his generation. Somerset v Stewart 98 ER 499, judgment of the Court of King\'s Bench in 1772 on labour law and human rights. British slave James Somerset); American, out of copyright.