After service in the Army he joined the civil service in the Native Land Purchase Office and rapidly rose in the Native Department and by 1910 he was a commissioner of the Native Land Court. He continued in the service of the Land Court, and the East Coast Native Trust for the rest of his working life, in 1923 becoming the first Maori judge of the Native Land Court. Carr, together with his patrons, Apirana Ngata, James Carroll and Peter Buck, was a main mover in the Maori faction which argued that the only way for Maori to survive and "progress" was to adopt as far as possible a European way of life, while retaining the more inoffensive picturesque aspects of their Maori-ness.