In the summer of 2019-2020, Australia was confronted with an unprecedented bushfire season that was followed, almost immediately, by the emergence of the COVID-19 pandemic. The Australian Constitution does not confer an express power on the Federal Government to deal with emergencies. In Australia, the management of emergencies is primarily the responsibility of the state and territory governments. The Federal Government has, however, utilised the Australian Defence Force (‘ADF’) to provide assistance to state and territory governments in responding to, and recovering from, the recent bushfires and COVID-19 pandemic. This paper examines the constitutional basis for the use of the ADF by the Federal Government in responding to emergencies. In particular, it considers the executive powers available to the Federal Government, in the absence of statutory authorisation, to deploy the ADF internally and explores how federalism operates to condition and limit these powers.