The Flanagin Law Office is a historic professional office building at 320 Clay Street in Arkadelphia, Arkansas. The front brick portion of the building was built in 1855 for Major J. L. Witherspoon, a local attorney, who later became Arkansas Attorney General and sat on the state's high court. Witherspoon took on Harris Flanagin as a partner; Flanagin served as Governor of Arkansas during the American Civil War, and used this building as a law office for many years. Flanagin's son had the wood-frame rear section added, converting the building into a residence. It has since been converted back to a law office.