David Johnston served as Minister for Defence in the Abbott Government from 2014, where he was a member of the Cabinet. Before this, he was Shadow Minister for Defence until the 2013 federal election. He also served as Shadow Minister for Resources, Energy and Tourism.

David began his political career with active involvement in the Liberal Party, including serving as State President of the Liberal Party of WA in 1997. Elected as a Liberal Senator for Western Australia in 2001, he entered the Senate in 2002. He contributed significantly to committees on defence and national security, including reviews on Materiel Acquisition and Management in Defence (2003) and the Effectiveness of Australia’s Military Justice System (2005).

In 2007, Prime Minister John Howard appointed David as Minister for Justice and Customs.

David is currently the Chair of the UWA Defence and Security Institute. Before this role, he served as the Australian Defence Export Advocate, promoting local defence industries internationally to secure export sales and contracts.