- In the recent case of Alexander v Minister for Home Affairs, the High Court found that controversial citizenship-stripping laws were partially invalid.
- By majority, the Court found that Australian Citizenship Act 2007, s 36B was constitutionally invalid and infringed the separation of judicial power. This means that anybody who was stripped of their citizenship under s 36B is an Australian citizen again.
- If a new challenge is brought by a person who lost their citizenship under s 33AA, it would have strong prospects of success.
In 2015, Australia introduced controversial new citizenship-stripping laws that applied to dual citizens deemed to have repudiated their allegiance to Australia. In 2020 these laws were amended, following significant criticism, including from government agencies. In June 2022, they were found partially invalid by the High Court in Alexander v Minister for Home Affairs  HCA 19.
A brief history of citizenship stripping in Australia
Australia’s citizenship-stripping laws were enacted as a national security device, in response to citizens travelling to serve as ‘foreign fighters’ for organisations like Islamic State. From their inception, the risk of constitutional invalidity hung over these laws, and minimising this risk was an active consideration in the drafting process.
The 2015 laws created two mechanisms via which a dual citizen could be stripped of their Australian citizenship. The first was conviction-based: where a dual citizen was convicted of particular national security offences under the Criminal Code (Cth), a ministerial discretion to revoke their citizenship was activated. The second was conduct-based and automatic: as soon as the citizen engaged in particular conduct, they were deemed to have repudiated their allegiance to Australia, and to have lost their citizenship.
The conduct that could trigger automatic citizenship loss was defined largely by reference to the same Criminal Code offences that formed the basis for conviction-based citizenship-stripping. The conduct-based provision was designed to allow for citizenship-stripping in two situations where obtaining a conviction was impractical: where the citizen had engaged in the relevant conduct in a foreign country, and where they had committed the conduct in Australia but had since left the country without prosecution. The automatic nature of conduct-based revocation was unique in the world and reflected an attempt to circumvent constitutional problems. It was thought that empowering a minister to revoke citizenship in the absence of a conviction would infringe the separation of judicial power, but that an automatic revocation mechanism might avoid such problems.