Born and educated in Perth in Western Australia, David attended Wesley College from 1967 – 1973 and then graduated from the University of Western Australia in 1981 with law degrees B.Juris LL.b.
David was elected to the Australian Parliament as a Senator for Western Australia in 2001 and was a Senator for 15 years.
Prior to that he was a Barrister and Solicitor in Western Australia practicing in the areas of Mining and Crime and lived and worked on the Eastern Goldfields of Western Australia for 12 years before returning to Perth to continue in the Law and as a Barrister and In-House Counsel providing advice and representation mainly pertaining to mining matters in Western Australia.
In Parliament David was inter alia, chair of the Senate Foreign Affairs Defence and Trade Committee, was appointed by Prime Minister Howard as Minister for Justice and Customs in 2007, was Opposition spokesperson as Shadow Minister on Minerals Energy and Tourism and then Defence from 2009 to 2013 and then Minister for Defence 2013 and 2014.
On 9 April 2018, Mr Johnston was announced as the first Australian Defence Export Advocate. The Australian Defence Export Advocate provides international advocacy for defence industry and will play an important role in delivering a national approach to export success.
David has a strong commitment to Australian Defence Industry and the current Australian Government’s budgetary support the Defence portfolio particularly focussing upon Australian naval ship and submarine building.
Mr Johnston currently sits on a number of boards including SAAB Technologies Australia, the Centre for Defence Industry Capability (CDIC advisory), and the Australian Strategic Policy Institute (ASPI).