[12] The Act is about "managing diseases and pests that may cause harm to human, animal or plant health or the environment" in Australia however has no jurisdiction within Australia as biosecurity is a sovereign right of the States under the Australian Constitution and s focused on preventing the entry of new pests and diseases and managing ‘Commonwealth land’ such as ports and defence force sites, There are chapters which cover management of risks in several areas, including:[5] Part 3 (Section 344) states that the Director of Human Biosecurity is the person acting in the capacity of Commonwealth Chief Medical Officer (CMO), and this person has certain powers conferred upon them by this Act.

[5][13] Chapter 8, Part 2 of the Act deals with "emergencies involving threats or harm to human health on a nationally significant scale".

The Health Minister may exercise special powers under this Part to deal with a human biosecurity emergency, subject to limits and protections.

The Act specifies that the Governor-General may declare such an emergency if the Health Minister (at the time Greg Hunt; as of October 2022[update] Mark Butler) is satisfied that "a listed human disease is posing a severe and immediate threat, or is causing harm, to human health on a nationally significant scale".

This gives the Minister sweeping powers, including imposing restrictions or preventing the movement of people and goods between specified places, and evacuations.

[2][13] The Biosecurity (Human Biosecurity Emergency) (Human Coronavirus with Pandemic Potential) (Emergency Requirements) Determination 2020, made by the Health Minister on the same day under Section 477 of the Act, banned international cruise ships from entering Australian ports before 15 April 2020.

[13] On 25 March 2020, the Health Minister made a second determination, the Biosecurity (Human Biosecurity Emergency) (Human Coronavirus with Pandemic Potential) (Overseas Travel Ban Emergency Requirements) Determination 2020, which "forbids Australian citizens and permanent residents from leaving Australian territory by air or sea as a passenger".

[16] On 5 April 2020, New South Wales Police launched a criminal investigation into whether the operator of Ruby Princess, Carnival Australia, broke the Biosecurity Act 2015 (Cwth) and possibly NSW state laws, by deliberately concealing COVID-19 cases.

[17] Late on 30 April 2021, after some days earlier imposing a ban on all flights from India, which was experiencing a dramatic rise in cases in a second wave of the COVID-19 pandemic, the Federal Government announced a ban on Australian citizens and permanent residents in India from entering Australia via any route.

[20] Foreign Minister Marise Payne reported that 57% of positive cases in quarantine had come from India in April, compared with 10% in March.