Carlos Coolidge graduated with honors from Middlebury College and began his law practice in Windsor. He served in the Vermont Militia and held various political positions, including State's Attorney for Windsor County and multiple terms in the Vermont House, serving as Speaker. Coolidge received honorary degrees from the University of Vermont and Middlebury College. He opposed the Mexican–American War and supported the Wilmot Proviso, reflecting his anti-slavery stance. During his governorship, he established a Supreme Court and Circuit Court System.

Carlos Coolidge's political career is marked by a complex blend of judicial reform and anti-slavery advocacy, tempered by a staunch opposition to territorial expansion. His establishment of a Supreme Court and Circuit Court System in Vermont demonstrates a commitment to legal infrastructure, while his anti-war and anti-conquest stances reveal a principled opposition to imperialism. Coolidge's support for the Wilmot Proviso and involvement in colonization societies highlight an unusual alignment of progressive abolitionism with a controversial resettlement agenda.