On 13 November 1954 at the Holy Family Catholic Church in Lindfield he married Elizabeth Margaret Moultrie Connolly.
He was called to the Bar on 8 February 1957 and specialised in land law, co-writing Landlord and Tenant Practice and Procedure in New South Wales (1958, 1966, 1971), a standard text in the area.
[2] He also sat on the state executive of the party until he resigned in 1972, believing that the election of the Whitlam Labor government marked the fulfilment of the DLP's objective.
Mackerras was also a supporter of the New England New State Movement, and also encouraged Asian immigration on the condition that it did not lead to an influx of communists.
However, this proved difficult for his family, and in 1975 they relocated to Kellys Plains, near Armidale, with Mackerras becoming a solicitor at Uralla.