Another Limb to the Lim Principle: Citizenship Stripping Legislation Declared Invalid
In November this year, the High Court held in Benbrika v Minister for Home Affairs  HCA 33 that s 36D of the Citizenship Act 2007 (Cth) is invalid for infringing an implied constitutional limit derived from the separation of powers. Section 36D provided that the Minister could determine in writing that a person ceases to be an Australian citizen if they were:
- convicted of certain listed criminal offences (including, relevantly, offences connected with terrorism);
- sentenced to a period of imprisonment of at least 3 years;
- the Minister was satisfied that the conduct of the person demonstrates that that they have repudiated their allegiance to Australia; and
- the Minister was satisfied that it would be contrary to the public interest for the person to remain an Australian citizen.
The key to understanding Benbrika is the holding in Chu Kheng Lim v Minister for Immigrationthat the “adjudgment and punishment of criminal guilt under a law of the Commonwealth” is an exclusively judicial function that could not be validly reposed in the Executive Government. Lim itself is presently undergoing something of a renaissance, having been applied in NZYQ to hold that Commonwealth legislation cannot validly authorise indefinite immigration detention. But as Benbrika shows, Lim is enjoying its moment in the constitutional sun in contexts well beyond executive detention.
Benbrika was a sequel to the decision in Alexander v Minister for Home Affairs, in which the majority held that s 36B of the Citizenship Act was invalid. Section 36B was very similar to s 36D, but, instead of operating where a person had been convicted of a criminal offence, it applied where the Minister was satisfied that the person had engaged in conduct which satisfied the physical elements of certain criminal offences. The majority in Alexander held that that s 36B was invalid because it empowered the Minister to exercise the exclusively judicial function of adjudging and punishing criminal guilt. Section 36B was held to be punitive, and therefore exclusively judicial, on the basis of the severity of the consequences it authorised, and its purpose, which was identified in broad terms as imposing retribution for, and deterrence of, reprehensible conduct inconsistent with a continued allegiance to Australia (such as terrorism).
The question in Benbrika was whether the holding in Alexander also applied to s 36D. The Minister contended that the Lim principle applied only to a law which authorises the Executive to adjudge and punish criminal guilt, rather than adjudge or punish criminal guilt. It was argued that s 36D (unlike s 36B) does not authorise the Minister to adjudge criminal guilt: instead, s 36D operates on a prior conviction by a Court. Alternatively, the Minister argued that the Court should identify a new exception to the Lim principle, identifying a number of precedents for the cessation of citizenship on conviction, and because the Executive was uniquely placed to make citizenship decisions.
The majority dismissed the Minister’s attempt to distinguish Alexander. Kiefel CJ, Gageler, Gleeson and Jagot JJ, Gordon and Edelman JJ each agreeing separately, held that the effect of Ch III of the Constitution is to make punishment of criminal conduct exclusively judicial, even if it is separated from the adjudication of that criminal guilt. It follows that the Parliament cannot repose in the Executive any function of sentencing persons convicted of offences against Commonwealth laws, or the power to impose additional or further punishments after conviction. None of their Honours accepted that there should be any new exception to the Lim principle.
Steward J dissented, as his Honour did in Alexander. His Honour concluded that s 36D was not punitive, because it was imposed only in respect of persons who had demonstrated, by their conduct, a fundamental repudiation of their allegiance to Australia. It followed that, for his Honour, no Ch III limit was engaged because the law was not properly characterised as punitive in character.
The decision in Benbrika is illustrative of the High Court’s increasingly assertive attitude to policing the separation of powers and other implied protections in Ch III of the Constitution. Given the wide range of laws imposing detriments on persons for criminal conduct – such as confiscation of the proceeds of crime, the cancellation of visas on character grounds, and the imposition of very large civil penalties – there may well be occasions on which the extent of Lim’s renaissance comes to be tested.
 (1992) 176 CLR 1.
 (2022) 96 ALJR 560.