AN0M in the High Court – CD v Commonwealth [2025] HCA 37
18.2.2026
‘Operation Ironside’ was one of the largest covert investigations by the Australian Federal Police (AFP) alongside overseas law enforcement authorities, into transnational and serious organised crime. The operation sounds like something straight out of a Hollywood movie. Operation Ironside involved the distribution of 921 mobile telephone devices throughout Australia between October 2018 and June 2021 which had installed on them an application known as ‘AN0M’. When users composed a message on the ANOM application and pressed ‘send’ to transmit the message to the intended recipient, a separate second message was created (which contained a copy of the first message alongside additional metadata) which was, unbeknownst to the sender, made available on a server accessible by the AFP (AN0M messages). Between October 2018 and June 2021, approximately 28 million AN0M messages were sent to the AFP server, leading to almost 1,000 arrests and 400 offenders being charged with offences. The AFP accessed the AN0M messages under warrants issued under the Surveillance Devices Act 2004 (Cth) and the Crimes Act 1914 (Cth).
As explained in more detail below in the Background section of this post, offenders began challenging the admissibility of the AN0M messages as evidence in their criminal proceedings on the basis that they were unlawfully intercepted in breach of the Telecommunications (Interception and Access) Act 1979 (Cth) (the TIA Act). Whilst this issue was pending in the High Court, Parliament passed legislation effectively retrospectively legalising the gathering of the AN0M messages and therefore increasing the likelihood of the messages being deemed admissible. The constitutionality of that legislation was challenged in the High Court.
The High Court’s decision in CD v Commonwealth [2025] HCA 37 (CD) confirms the Court’s consistent approach to determining the validity of legislation when challenged on the basis that it either constitutes an impermissible exercise by the Parliament of the judicial power of the Commonwealth or because it impermissibly interferes with and undermines the institutional integrity of courts vested with federal jurisdiction. The Court in its decision expressed a hesitation to characterise provisions dealing with the admissibility of evidence as interfering with judicial power, notwithstanding that the admission of that evidence could prove determinative in a finding of an accused person’s guilt. Put another way, and perhaps uniquely, the Court’s focus on form in characterising the legislation at issue suggests that Parliament has available a broad suite of tools to influence the exercise of judicial power without it constituting either an exercise of, or an impermissible interference with, that power.
Background to the Case
CD and TB (the Plaintiffs) were arrested and charged with offences under the Criminal Law Consolidation Act 1935 (SA) and Firearms Act 2015 (SA) for participating in a ‘criminal organisation’ and for possession of prohibited items. The Plaintiffs were part of a group of more than 390 people who were arrested and charged with various offences as part of Operation Ironside. The Plaintiffs have been in custody since their arrest.
On 5 December 2022, the Plaintiffs filed an interlocutory application in the Supreme Court of South Australia seeking that the AN0M evidence be excluded from their trials on the basis that they were unlawfully intercepted in breach of the TIA Act. Both the trial judge and then on appeal, the Court of Appeal of the Supreme Court of South Australia, held that the relevant communications were not intercepted contrary to the TIA Act.
The Plaintiffs then sought special leave to appeal from the Court of Appeal’s decision, which the High Court granted on 7 November 2024 (A24/2024) (the Appeal Proceeding).
A fortnight after the High Court granted special leave in the Appeal Proceeding, the Commonwealth Attorney General introduced into Parliament the Surveillance Legislation (Confirmation of Application) Bill 2024 (Cth), which was passed by both houses of Parliament on 28 November 2024 (the Confirmation of Application Act). The Confirmation of Application Act received Royal Assent on 10 December 2024 and commenced on 11 December 2024. The Confirmation of Application Act purports to deem communications obtained under specified warrants not to have been intercepted while passing over a telecommunications system (and therefore not to be intercepted contrary to the TIA Act) and to have been lawfully obtained under those warrants. In effect, the Confirmation of Application Act confirmed the decision of the Court of Appeal whilst the appeal to the High Court on the same questions was pending. On 7 January 2025, the Plaintiffs challenged the constitutional validity of the Confirmation of Application Act in the original jurisdiction of the High Court (A2/2025) (the Constitutional Proceeding) on two grounds:
a. the Confirmation of Application Act is invalid because it is an impermissible exercise by the Parliament of the judicial power of the Commonwealth and thereby is an invalid usurpation of judicial power by the Parliament; and
b. the Confirmation of Application Act interferes with and undermines the institutional integrity of courts vested with federal jurisdiction.
The Confirmation of Application Act
It is necessary at the outset to understand the provisions of the Confirmation of Application Act and their operation. Thankfully, that Act constitutes a total of seven provisions. The key provisions are described in turn.
Section 4 contains definitions including relevantly that ‘intercepting a communication passing over a telecommunications system has the same meaning as in the’ TIA Act and ‘intercepted while passing over a telecommunications system has a corresponding meaning’. The definition of ‘relevant warrant’ identifies in a list the warrants relied upon by the AFP to obtain access to the AN0M messages and the data related to them.
Section 5 is the main provision which was challenged by the Plaintiffs. Most importantly, subsection (1) provides that information or records obtained under a ‘relevant warrant’ are taken not to have been ‘intercepted while passing over a telecommunications system’. Subsection (2) provides that any actions which would have been invalid or unlawful except for subsection (1) are taken to have been valid and lawful. Subsection (3) provides that evidence that would otherwise have been wholly or partly obtained improperly or in contravention of Australian law is taken not to have been and always not to have been so obtained.
Section 6 has a similar structure and is expressed in similar terms to section 5, but instead effectively deems evidence obtained in reliance or purported reliance on a ‘relevant warrant’ to have been so obtained, and provides a relevantly identical deeming provision with respect to contraventions of Australian law and impropriety. Whilst section 6 was also challenged by the Plaintiffs, they accepted that their challenge was linked to, and could not be maintained independent from, their challenge to section 5.
Section 7 confirms the application of the Confirmation of Application Act to civil and criminal proceedings including, relevantly for the purposes of this case, proceedings commenced prior to the commencement of the Act which have not yet concluded.
Despite its apparent complexity and repetitive nature, the purpose of the legislation was clear. In substance, the legislation sought to ensure that to the extent the AN0M messages obtained during Operation Ironside were unlawfully intercepted under the TIA Act and therefore inadmissible as evidence in criminal proceedings, they were no longer considered as such. In other words, it retrospectively treated any conduct in gathering those messages as lawful. That would not necessarily result in the messages being deemed admissible—for example, they could be deemed inadmissible on relevance grounds—but it undermined a challenge to admissibility on the grounds that the evidence was obtained unlawfully in breach of the TIA Act.
The High Court’s Judgment
The High Court unanimously held that the Confirmation of Application Act was valid—Edelman J characteristically writing separately but agreeing with the remaining judges constituting the majority. In light of its answers in the Constitutional Proceeding, the Court revoked special leave in the Appeal Proceeding.
The Court relevantly held that on its proper characterisation, section 5 of the Confirmation Act is indistinguishable from the laws held to be valid in Nicholas v The Queen (1998) 1983 CLR 173 (Nicholas) and Duncan v Independent Commission Against Corruption (2015) 256 CLR 83 (Duncan).
Nicholas concerned a provision which intended to reverse the effect of the High Court’s decision in Ridgeway v The Queen (1995) 184 CLR 19 by providing that, subject to certain conditions, the admissibility of particular evidence was to be determined by disregarding the fact that a law enforcement officer committed a particular offence in obtaining that evidence. The majority in Nicholas held that the relevant provision was valid primarily on the basis that it was fundamentally an evidentiary provision (and as such did not involve Parliament adjudicating on any ultimate fact) and because the legislation did not target any one person or a small group of persons. Justice Toohey explained this clearly, stating that there is no question that legislation can affect the way in which judicial power is exercised including by requiring particular evidence to be treated in a particular way. What a court must do in determining whether this goes too far is to look at the consequences of the operation of the legislation and whether, for example, the effect of the legislation would undermine the idea of a fair trial to such an extent that it would go beyond the power of Parliament. In Nicholas, that was clearly not the case as the legislation simply dictated the admissibility of evidence in the particular case where narcotic goods were imported into Australia. Quoting from his Honour’s judgment, the impugned provision ‘is an evidentiary provision. It does not determine whether a charge of an offence…will succeed or fail’.
Duncan concerned an amendment to the Independent Commission Against Corruption Act which was made after the High Court’s decision in Independent Commission Against Corruption v Cunneen (2015) 256 CLR 1. The Independent Commission Against Corruption Amendment (Validation) Act 2015 (NSW)was intended to ensure the validity of the Independent Commission Against Corruption’s (ICAC’s) activities despite that decision in an action brought by Mr Duncan, in circumstances where he would otherwise have been able to rely on Cunneen. The majority in Duncan held the legislation to be valid on the basis that the impugned provisions simply altered the substantive law as it applied to acts done by ICAC before 2015 and that legislation was not directing the courts to treat invalid acts as valid but rather retrospectively conferring on ICAC the authority to do those historical acts. Put more simply, the legislation did not in any way require a court to dismiss or disregard a law in a particular circumstance but instead amended the law retrospectively. The judicial power remained the same—to follow and apply the law at the time a controversy came before it.
In CD, the majority (at [22]) emphasised that the existence of ongoing legal proceedings (here, the Appeal Proceeding) presented no prohibition against legislative declaration or action (citing R v Humby; Ex parte Rooney (1973) 129 CLR 231 at 250). The majority (at [25]) characterised section 5 of the Confirmation of Application Act as effectively a simple evidentiary provision—that is, it facilitated the admission of evidence which may otherwise have been excluded by statute or under common law. The Court made clear that the Act had no role in judging criminal guilt or civil liability nor establishing any of the elements of an offence. Instead, section 5 simply established new legal consequences to a given fact, being the obtaining of information under a ‘relevant warrant’. Justice Edelman shared the interpretation of the operation of the Confirmation of Application Act set out by the majority (at [63)]. His Honour further noted that this legislation did not apply to a group of identified persons. Notwithstanding that it undoubtedly impacted the 390 people who were charged, it could apply to others in the future if further charges are laid.
Accordingly, the Court held that the Confirmation of Application Act was valid as it is not an impermissible exercise by the Parliament of the judicial power of the Commonwealth and does not impermissibly interfere with and undermine the institutional integrity of courts vested with federal jurisdiction.
Is it Possible to Define Judicial Power?
Notwithstanding the brevity of the judgment and relative simplicity of its reasoning, the Court made some interesting observations about the scope of judicial power and whether it is possible to subject it to some definition.
The majority effectively accepted that it was not capable of definition—in their words, ‘it defies exhaustive definition’ (at [15]). Accordingly, they said it ‘is not possible to state any formula of words against which future legislation may be tested to ascertain if it involves an exercise of or an impermissible constraint on the exercise of judicial power’ (at [16]). Nevertheless, the Court quoted from its previous decisions various descriptions of aspects of judicial power (at [15]). These included things such as the final and authoritative quelling of controversies involving rights and liabilities and adjudgment of criminal guilt including fact finding incidental with that role. In a similar vein, Edelman J said that the ‘point at which an Act of a Parliament will cease to be properly characterised as an exercise of legislative power and be characterised as a wrongful appropriation of judicial power’ is ‘notoriously difficult to identify’ (at [54]). Similarly, his Honour said that ‘[t]he categories of case that can amount to an undue impairment of judicial power are not closed’ (at [65]).
Where does that leave us? Much like in this case, drawing comparisons between challenged legislation and legislation held to be valid (or invalid) in previous cases proves critical. That appears to be the most fruitful method of argument in cases challenging the validity of legislation on the grounds presented in this case. Accepting that those are not limiting, understanding the factors that led to legislation in those cases being deemed valid or invalid, as the case may be, is an important exercise. Professor Gerangelos (found here) suggests the following relevant factors:
a) whether the legislation is ad hominem or targeted at an identified or identifiable class of persons;
b) the specificity of the legislation with respect to pending litigation including the timing of the enactment;
c) the retrospective nature of the legislation;
d) who the parties to the litigation are, including whether the government is a party to the pending proceedings or has a particular interest in them.
To that list it may be added whether the legislation can be characterised as operating effectively as an evidentiary provision. That much was probably true after Nicholas, but the Court’s focus on this idea in its analysis in CD entrenches it as a highly relevant, if not decisive, factor. Importantly, the Court in this respect appears to approach the characterisation of a provision as evidentiary in nature on its face, with limited consideration of its practical impact. In this case for example, given the incriminating nature of the AN0M messages, it is no doubt that the likelihood of a successful conviction would depend significantly, if not entirely, on whether those messages were admitted into evidence. In that sense, one could argue that the practical effect of the legislation was indeed to adjudicate guilt given the retrospective validation of conduct which would otherwise prohibit admission of such incriminating evidence. Given this approach the Court has taken, albeit implicitly without any suggestion of preferring form over substance, Parliament appears to have been provided a broader suite of tools to shape the contours and exert influence over the exercise of judicial power through legislation without the Court characterising such legislation as constituting either an exercise of, or an impermissible interference with, that power.
Unfortunately, beyond this, the scope of judicial power remains incapable of clear formulation. Practitioners should continue to have recourse to previous decisions and attempt to characterise or distinguish legislation through the language of categories of legislation held not to constitute an exercise of judicial power such as ‘evidentiary provisions’. Doing so appears to be the most fruitful way to persuade the Court that particular legislation involves or does not involve either an exercise of, or an impermissible interference with, judicial power, noting that that power, in the Court’s words, ‘defies exhaustive definition’.
Rohan Balani is a Master of Laws (LL.M.) candidate at Columbia Law School. All views are his own.
Suggested citation: Rohan Balani, ‘AN0M in the High Court – CD v Commonwealth [2025] HCA 37’ (18 February 2026) <https://www.auspublaw.org/blog/2026/2/an0m-in-the-high-court-cd-v-commonwealth-2025-hca-37>