Immigration detention is the mandatory holding of a person who is an unlawful non-citizen under section 189 of the Migration Act 1958. A person becomes an unlawful non-citizen when they are in Australia without a valid visa, including when their visa has expired, been cancelled, or been refused. Unlike criminal detention, immigration detention does not require a court order and is not a punishment. It continues under section 196 until the person is removed from Australia, deported, or granted a visa that allows them to remain. Australia has no statutory time limit on immigration detention.

