As Lieut-Bailiff, Le Geyt was effectively in charge of the Royal Court and States in an era when successive members of the Carteret family held the office of Bailiff but had little or nothing to do with the island’s administration.
He was the eldest son of Philippe Le Geyt, Jurat, and Jeanne Seale. Born in the Vingtaine of Mont a l'Abbe, St Helier, in 1655, his boyhood was spent in the turmoil of the Civil War. He saw his home plundered by Parliamentarians, and the furniture destroyed. His Royalist father was in Elizabeth Castle when it surrendered in 1651, and to escape confiscation of his property compounded by paying two years' income.
The lad went to the Huguenot University at Saumur, and then took the Law course at Caen and Paris. He returned to Jersey, where his father, no longer a Jurat, had been living quietly under the Commonwealth regime. At the Restoration his father resumed his seat on the bench, and Philippe was appointed Greffier on 27 September 1660, a post which his father had held before him; and, when his father died, he was elected without opposition to succeed him as Jurat on 20 January 1670. In the following year he went as one of three Deputies to represent the States before the Privy Council.
The Council had sent some Orders meant to improve the administration of justice. The Court had given them a trial, and found them unworkable. An appeal to the Council had secured only slight alterations. So this deputation was sent. After waiting 15 months in London, they returned with nothing accomplished.
Sir George Carteret wrote that he had done his best to secure an interview for them, "but the attention of the Lords of the Council is absorbed by the War and by great questions of state now under discussion, and they have no time for less important matters".
In 1676, when Jean Poingdestre resigned the post of Lieut-Bailiff, Le Geyt was appointed in his place. This was no sinecure, for Sir Edouard de Carteret, the Bailiff, was Gentleman Usher of the Black Rod, and his Court duties kept him from the island. His successor, Sir Philippe De Carteret, also appointed Le Geyt his Lieutenant, and, when Sir Philippe died, he acted as Juge-Delegate during the interregnum; so that for 18 years he was Chief Magistrate of the island and President of the States.
He was the best jurist that Jersey Law produced, with a profound knowledge of Roman Law, of the old Norman Coutumiers, and of the precedents of his own Court. From the moment he became a judge he abstained (an unusual thing in Jersey both before and since) from taking part in politics, lest he should be suspected of partiality. In 1686 he presented to St Helier's Church a silver baptismal dish.
The Revolution of 1688 threw upon him a difficult task. There were grounds for thinking that James II had some idea of holding the island, as his brother had done, even if he lost England. He appointed a Roman Catholic Lieut-Governor, and garrisoned Elizabeth Castle with Roman Catholic troops. But Le Geyt quietly insisted that the local Militia should be admitted to help to defend the Castle; and, when the Prince of Orange landed in England, a Protestant Regiment was sent to Jersey, and the Roman Catholic soldiers were disarmed.
When Edouard De Carteret became Bailiff in 1694, Le Geyt asked to be relieved of his work as Lieutenant; but he retained his Juratship until 1711. He now had leisure for writing. He had already in 1692 composed his Procede des Commissaires Pyne et Napper, a work invaluable to Jersey historians. His other most important writings were his Traite des Temoins (1696), which Sir Robert Marett considered his greatest claim to the gratitude of posterity ; Remarques sur quelques Loix et Coutumes de l'Ile de Jersey (1697); Traite des Commissaires Royaux (1698); Traite des Crimes, in the course of which he urged schoolmasters to take their pupils to see every execution to impress on them a horror of crime; and Sentences et Quaestions.
The treatise on Privileges, Lois, et Coutumes de l'Ile de Jersey et Reglements Politiques, commonly known as the Code Le Geyt, a work of great merit, was almost certainly his work though his authorship has been questioned.
He never married, and in old age he lived with his nephew Philippe Le Geyt. He died on 31 January 1716, and was buried in the Town Church. His friend Baptiste Sorsoleil, Rector of St Lawrence, summed up his character thus:
- "He was a man of the old-fashioned school of virtue. In him knowledge, courtesy, and probity were inseparably joined to love of religion and zeal for justice".
For many years his writings circulated only in manuscript copies, but in 1841 the original manuscripts were bought by Dean Jeune, and offered by him to the States, who printed them in four volumes: