The eldest son of John de Gex of Leicester Place, Middlesex, his family background was Swiss, his father having settled in England about the beginning of the century.
The question was whether the Duke of Newcastle, not being engaged in trade, was exempt from the operation of the law of bankruptcy on the ground of his being a peer.
The case was argued before the Court of Appeal, De Gex being leading counsel for the appellant, and Sir Roundell Palmer representing the duke.
[2] De Gex took silk on 28 March 1865, with Joshua Williams and George Jessel;[3] and then on 19 April he was elected a bencher of his inn.
In 1882 he was elected treasurer of Lincoln's Inn, and in December of the same year he was knighted on occasion of the opening of the new law courts.
In 1852 he published a volume of Cases in Bankruptcy decided by the Court of Review, Vice-chancellor Knight-Bruce, and the Lord-chancellors Lyndhurst and Cottenham.
[2] In 1867 De Gex published, in conjunction with Horton Smith, Arrangements between Debtors and Creditors under the Bankruptcy Act, 1861, London.
[2] De Gex married in 1880 Alice Emma, eldest daughter of Sir John Henry Briggs.