Released at the war's end in 1865, Lafoon taught school for two years. He then studied law, and was admitted to the bar in 1867, practicing in Madisonville. He served as the prosecuting attorney for Hopkins County.
Laffoon was elected as a Democrat to the Forty-ninth and Fiftieth Congresses (March 4, 1885 – March 3, 1889). He served as chairman of the Committee on Expenditures in the Department of War (Fiftieth Congress). He did not seek reelection in 1888.
Lafoon resumed his law practice in Madisonville, dying there on October 22, 1906. He was interred in the Odd Fellows Cemetery at Madisonville. His nephew, Ruby Laffoon, served as Governor of Kentucky from 1931 to 1935.