Born in Burlington, Vermont, Coffrin received an Artium Baccalaureus degree from Middlebury College in 1941 and was a lieutenant in the United States Navy during World War II, from 1942 to 1945.

He again served in the Navy during the Korean War, from 1951 to 1952, thereafter returning to private practice in Burlington until 1972.

[1] On May 3, 1972, Coffrin was nominated by President Richard Nixon to a seat on the United States District Court for the District of Vermont vacated by Judge Bernard Joseph Leddy.

Coffrin was confirmed by the United States Senate on June 8, 1972, and received his commission the next day.

He served as Chief Judge from 1983 to 1988, assuming senior status on January 31, 1989, and serving in that capacity until his death on January 13, 1993, in Burlington.