William B. Caldwell was born on a Butler County, Ohio farm, where he stayed his first 21 years.

[1][2] He studied law under John Woods of Hamilton, Ohio, and was admitted to the bar in 1837.

[1][2] In autumn 1851, a new constitution of the state made judges elective, and Caldwell received the most votes among 11 candidates for five positions on the court.

[3] The five winners drew lots, and Caldwell was assigned a one-year term.

[5] Caldwell resigned his seat in December, 1854,[4] and resumed his practice in Cincinnati.