William Barclay, a Scottish jurist, born in Aberdeenshire in 1541 or 1546, died at Angers, France, in 1605. He studied law at Bourges, under Cujas, and received the degree of doctor of laws, He was soon after appointed professor of the civil law in the university of Pont-a-Mousson, then recently founded by the duke of Lorraine. He was also made counsellor of state and master of requests. Having quarrelled with the Jesuits on account of his refusal to let his son enter the society, he lost favor, went to England, and was offered a professorship of law upon condition that he would renounce the Roman Catholic faith. This he refused, and returned to France, where he was made professor of law at Angers. During the troubles of the league ho supported the royal cause and was uniformly an opponent of the ultramontane doctrines. His principal works are: De Regno et Regali Potentate (Paris, 1600); a commentary on the title of the Pandects De Rebus Creditis et de Jure Jurando; and a treatise De Potestate Papas (London, 1609), in which the independent rights of sovereign princes against the pope are vindicated.