A descendant of both John Winthrop, first Governor of Massachusetts, and John Winthrop, the Younger, first Governor of Connecticut, immediately after graduating he became a personal secretary to future president William Howard Taft while Taft was Governor-General of the Philippines. Winthrop was soon promoted to Assistant Executive Secretary of the Philippines (1901–1903) and was appointed as a Judge of the Court of First Instance, Philippine Islands (1903–1904).
A descendant of both John Winthrop, Massachusetts' first governor, and John Winthrop, Connecticut's first governor, immediately after graduation he became William Howard Taft's personal assistant while Taft was Governor-General of the Philippines. Winthrop was soon elevated to a high-ranking position in the Philippines (1901–1903) and later appointed as a judge in the Philippine Islands' court system (1903–1904).