William Smith (the younger) was born on June 18, 1728 in New York City and was educated at Yale College, from which he graduated in 1745. With fellow students William Livingston and John Morin Scott, Smith studied law in his father's law office and was admitted to the New York bar on October 22, 1750. Smith and Livingston formed a very successful law practice and in a 1764 landmark case, Forsey v. Cunningham, they represented Waddell Cunningham while John Morin Scott represented Forsey. When Governor Colden tried to interfere in the jury verdict in the case, the three young lawyers vigorously opposed his attack on the common law. Despite Smith's thwarting of the Governor, when William Smith, the elder, indicated that he wished to retire from the Governor's Council in 1767, William Smith, the younger was appointed to the office his father had held.
Many promising young lawyers of the time chose to study law with Smith, including Robert R. Livingston, Gouverneur Morris and George Clinton. William Smith compiled the first collection of the Laws of New-York from the year 1691 to 1751 and this work was published in 1752. He also authored The History of the Province of New-York which was published in London in 1757.
In 1776, William Smith moved to upstate New York in the hope of staying out of the politics of the time but two years later he declared his support for the loyalist cause, and joined the British in New York City. In 1780, Smith was appointed Chief Judge of New York but this office, in reality, pertained only to that part of the Province that was still in British hands.
When the British evacuated New York in 1783, Smith sailed for England to seek compensation for his property which had been seized by the State of New York. While in England, Smith was offered the office of Chief Judge of Quebec, Canada, and on October 23, 1786, shortly after landing there, he took the oaths of office as councillor and chief justice.
William Smith died on December 6, 1793 in Quebec City.
L. F. S. Upton, “SMITH, WILLIAM (1728-93),” in the Dictionary of Canadian Biography (1979)