After completing his law degree in December 1982, Coltart returned to Zimbabwe and in January 1983 went to work for the Webb, Low and Barry law firm in Bulawayo. He was admitted as a Legal Practitioner of the Zimbabwean High Court in February 1983. In April of that year he established the first Legal Aid Clinic in Bulawayo. He was appointed a partner of Webb, Low and Barry in 1984 and became the firm's senior partner in 1998, a position he still holds.