John Tabor Kempe was born in England, the son of New York Attorney General William Kempe who came to the Province with his family in 1752. Kempe studied law with James Alexander, one of the leading lawyers in the Province, and was admitted to the New York bar in 1758. Upon the death of his father in 1759, John Tabor Kempe was appointed Attorney General of New York, the last to receive a royal commission.
During the Seven Years' War (the French and Indian War), sixteen prominent New York merchants were charged with high treason for trading with the enemy. The first of these cases, Crown v. Cunningham and White, commenced in April 1763 and the defense relied on the argument that the defendants' actions were commonplace during the war. The jury returned a guilty verdict and the court imposed a substantial fine on the defendants. The defense sought an “arrest of judgment” based on the severity of the penalty and in a later proceeding, the fine was substantially reduced.
Three months later, Cunningham was involved in an altercation with an Albany merchant, Thomas Forsey. Cunningham was prosecuted and found guilty of criminal assault and Forsey then brought a civil action for damages, Forsey v. Cunningham. The jury found in favor of Forsey and Cunningham attempted to appeal to the Council. Acting Governor Colden sought a legal opinion from Attorney General John Tabor Kempe and while the Governor did not abide by Kempe's advice that the jury verdict could only be challenged through a writ of error, the Attorney General would later see his position confirmed by a joint opinion of the English Attorney General and the Solicitor General.
Through marriage, John Tabor Kempe came into possession of a large landed estate and over time became one of the wealthiest men in the Province. A Loyalist during the Revolutionary War, Kempe remained in New York but when a peace was agreed, Kempe was attainted for treason in both New York and New Jersey and his properties were confiscated. Kempe sailed for England where he lived until August 1792, when he was thrown from his carriage and died.
In 1825, John Tabor Kempe's heirs obtained passage of a bill in the New York Legislature that restored to them his house, stables and grounds on the northeast of Greenwich Street in New York City. Their efforts to have the New Jersey estates restored to them led to litigation and the case eventually came before the Supreme Court of the United States in Kempe's Lessee v. Kennedy, 9 U.S. 173 (1809).
Thomas M. Truxes. Defying Empire: Trading with the Enemy in Colonial New York (2008)
New-York Historical Society. The Papers of William Kempe and John Tabor Kempe