He was born on August 17, 1728 in Boston, Massachusetts, United States, the son of Jonathan and Mary (Payne) Sewall. The first of his ancestors to come to America was his great-grandfather, Henry Sewall, who emigrated in 1634 and the following year settled in Newbury, Massachussets, but later returned to England. By 1681 the family was permanently established in Salem, where Jonathan's grandfather, Stephen, died in 1725.
After his graduation from Harvard in 1748, hehad a minimum of legal training.
He set up an office in Charlestown. In the pursuit of his profession he frequently came into contact with John Adams.
On the death in 1760 of his uncle, Stephen Sewall, chief justice of the superior court, the young lawyer undertook the administration of the estate. Finding his uncle's affairs badly involved, he appealed to the General Court for a grant of money with which to satisfy the creditors. The refusal of the Court to grant this petition apparently alienated him from the cause of the patriots.
He was first made solicitor general, then, in 1767, attorney general, and in 1768 judge of the vice-admiralty court of Halifax. On Governor Hutchinson's departure from Massachusetts, Sewall was one of the signers of the barristers' address to him. Close upon this open display of his allegiance to the royal government came a conversation between Sewall and Adams which marked the irreparable rift between the friends.
In September 1774 Sewall left his Cambridge home for Boston, from which place he sailed for England early in 1775. His name was included in the act of banishment of 1778 and his property was declared forfeited the next year. For a time he remained in London, one of the group of Loyalists who dined together weekly while they waited for word that the Revolution was crushed and that they might return from their exile.
While in London he changed the spelling of his name to Sewell. In 1777 he removed to Bristol where, save for brief excursions, he resided until 1788. In that year he embarked for Halifax, with the hope, as he told John Adams in a brief reunion with him in London, of making provision for his children. This hope he was able to fulfil.
Sewall himself died in St. John, New Brunswick, never having revisited his native land.
Jonathan Sewall was one of the signers of the barristers' address to court of Halifax, for which he was expelled and never revisited his native land. In his legal practice he was famous for his case of James vs. Lechmere, as he gained a decision in favor of the freedom of a slave two years before Lord Mansfield's famous decision in the Somerset case. Under the names Philanthropos and Long J. , he was a frequent and suciessful contributor to the press, to him also was attributed the writing of well-known Gage's proclamations.
Sewall, convinced of the speedy defeat of the colonists, urged Adams to abandon his intention of attending the Philadelphia congress.
Quotes from others about the person
Of Sewall's abilities John Adams thought highly: "He possessed a lively wit, " Adams wrote, "a pleasing humor, a brilliant imagination, great subtlety of reasoning, and an insinuating eloquence".
On January 21, 1764 he married Esther Quincy. His elder son, Jonathan, became chief justice of Lower Canada; the younger, Stephen, became solicitor general.
