He was an early member of the Mattachine Society, involved with the first attempt to pass a human rights ordinance inclusive of sexual orientation in New York City, and co-founder of Triangle Foundation (today known as Equality Michigan).

[2][3] Messer met his life partner, Carl House, while serving as a captain in the United States Army Air Forces.

During the war, he was stationed at Maxwell Air Force Base in Montgomery, Alabama, and began his specialization in neurosurgery under orders from his commanding officer.

[2] After resigning from the Air Force, Messer completed his residency and then practiced neurosurgery at Saint Vincent's Catholic Medical Center in Greenwich Village.

Clingan and Councilman Carter Burden introduced a bill in 1971, which Messer helped author, that would have prohibited discrimination in employment and housing on the basis of sexual orientation in New York City.

[2] After moving to Michigan in 1976, he became involved with the Association of Suburban People (ASP) as a board member and public face of the organization.

Messer later became involved with the Michigan Organization for Human Rights (MOHR) as a board member and proponent of lobbying elected officials and holding them accountable to their LGBT constituents.

[2] Messer was arrested in January 1985 by an undercover police officer at the Irving Art Theater for alleged indecent behavior.

[11] Messer received the Lifetime Achievement Award at the annual Southeast Michigan LGBT Pride Banquet on June 15, 1995.

[4] State Representative Patricia Godchaux requested, and received, a tribute to the couple on their 50th anniversary from Michigan Governor John Engler.