John R. Dethmers
46th, 50th, and 53rd Chief Justice of the Michigan Supreme Court
In office 1967–1969
Preceded by	Thomas M. Kavanagh
Succeeded by	Thomas E. Brennan
In office 1956–1962
Preceded by	Edward Sharpe
Succeeded by	Leland W. Carr
In office 1953–1953
Preceded by	Clark Adams
Succeeded by	Henry Butzel
69th Justice of the Michigan Supreme Court
In office 1946–1970
Appointed by	Harry F. Kelly
Preceded by	Raymond Starr
Succeeded by	Swainson/Williams
43rd Michigan Attorney General
In office 1945 – August 15, 1946
Governor	Harry Kelly
Preceded by	Herbert J. Rushton
Succeeded by	Foss O. Eldred
Chairman of the Michigan Republican Party
In office 1942–1945
Ottawa County Prosecuting Attorney
In office 1931–1938
Personal details
Born	(1903-10-15)October 15, 1903 Plessis, Iowa
Died	November 1, 1971(1971-11-01) (aged 68) Lansing, Michigan

John R. Dethmers (October 15, 1903 – November 1, 1971) was a politician from the U.S. state of Michigan.^[1]

Dethmers was born in Plessis in O'Brien County, Iowa. He resided in Orange City, Iowa, Holland, Michigan, and East Lansing, Michigan. He enrolled at Hope College in Holland, Michigan, then went on to the University of Michigan Law School and began to practice law in 1927. Dethmers was a member of various judicial associations and was a family man with three children. He was Ottawa County Prosecuting Attorney from 1931 to 1938. He was a member of the Michigan Republican State Central Committee in 1939. Dethmers served as Chairman of the Michigan Republican Party from 1942 to 1945 and was a delegate to the 1944 Republican National Convention. He served as Michigan Attorney General from 1945 to 1946. Governor Harry Kelly appointed Dethmers Justice of the Michigan Supreme Court, serving from 1946 to 1970 and serving as Chief Justice of the Michigan State Supreme Court in 1953, 1956–1962, and 1967–1969. He was defeated in 1970. He was a Presbyterian and a member of the American Judicature Society. John R. Dethmers died in Lansing.