Dewey, Henry Sweetser was born on November 9, 1856 in Hanover, New Hampshire, United States. Son of Major Israel Otis and Susan Augusta (Sweetser) Dewey.
Bachelor of Arts, Dartmouth, 1878, A.M., 1879. Bachelor of Laws, Boston University, 1882. Also read law in office of Honorary Ambrose A. Ranney.
Admitted to bar, 1882, later to the United States Circuit and Supreme Court of the United States courts.
Member, 1891, chairman, 1895, Board Bar Examiners for Suffolk Company. Member Republican ward and city committee, City of Boston, 1884-1888. Member Boston Common Council, 1885, 86, 87.
Member Massachusetts House of Representatives, 1889-1891. Served in Massachusetts 1st Corps of Cadets, 1880-1889. Member Bar Association City of Boston, American Bar Association, International Law Association, Alpha Delta Phi, Loyal Legion, S.R., Society Colonial Wars.
Congregationalist.; Clubs: Alpha Delta Phi (New York), University, Athletic (Boston). Member Wissenschaftlichen Klub, Vienna, Austria.