Thomas Law was born in Cambridge, England into an aristocratic family. His father, Edmund Law, was the Lord Bishop of Carlisle. Two of his brothers, John and George Henry, also became bishops; his brother Ewan was a member of Parliament from 1790-1802, and his brother Edward was Attorney General and Speaker of the House of Lords.Thomas Law served as an official of increasing rank with the British East India Company in Bengal, India, from 1773 to 1791, where he became acquainted with Lord Charles Cornwallis. Law eventually became a judge and revenue collector for the district of Bahar, where he won acclaim for reforming the tax system, and received significant financial benefit. Law came to America in August, 1794, seeking opportunities for the investment of his fortune. In New York, he met James Greenleaf and purchased 500 lots, becoming a primary developer of the new Federal City of Washington, DC. Shortly after he arrived in Philadelphia, Law met Martha Washington's granddaughter, Elizabeth "Betsey" Parke Custis, the eldest child of John Parke Custis and his wife Eleanor Calvert. Though he had already three young mixed-race sons from a union in India, he married Elizabeth Parke Custis on March 21, 1796. The Laws brought two of his sons to America to live with them, and soon had a daughter, Eliza Parke Custis Law Rogers (1797-1822). Differences in temperament led to the Laws’ separation. Law returned to England between 1802 and 1804, the couple legally separated in 1804, and divorced in 1811.