Mackinnon Jacobs Lawyers originated in 1919, when Duncan Mackinnon established a practice after returning from Word War I. The firm, then known as Mackinnon & Colles and located in Queen Street, Melbourne, soon moved to new offices in Collins Street and became Duncan Mackinnon & Co. Although Duncan Mackinnon died in 1957, his name has been retained as an acknowledgment of his founding contribution to the firm.
In 1952, upon return from World War II and following the completion of his law course, Clifford Jacobs was invited into partnership with Duncan Mackinnon. In 1958, he established a branch office in Boronia and, in the mid-1960s, moved the city office to Richmond. For a brief time, the firm was known as Mackinnon Jacobs & Irving.
In 1983, the firm merged with Lew Horton & Co. and, with new partner Richard Horton at the Boronia office, became Mackinnon Jacobs Horton & Irving Pty and later Mackinnon Jacobs Horton & Irving Pty Ltd.
In 1997, to meet increasing growth and demand in the eastern suburbs, a third office was established at Rowville.
In 2006, the Richmond office moved back to Collins Street. In 2009, it moved to Queen Street, then later to premises in Little Collins Street in 2014.
Partnership was accepted by Richard Kent in 2006.
Richard Horton retired from the partnership in 2007 but continued as a consultant to the firm until 2012.
Michael Jacobs retired from the partnership in 2018 but continues as a consultant to the firm.
The firm currently trades under the name Mackinnon Jacobs Lawyers. It is well placed to offer personalised attention to clients with a wide range of legal concerns.