This study revealed a substantial increase in awareness of the ACT's multi‐drug decriminalisation reform among people who regularly use illicit drugs in Canberra, rising from modest pre‐implementation levels to clear majorities in both samples 6–8 months after the reform took effect. However, understanding of the reform remained mixed. Many participants mistakenly believed that substances other than cannabis were ‘entirely legal’ to possess in small quantities, indicating potential confusion between decriminalisation and legalisation. We further showed misinterpretations about potential police and magistrate responses for both possession of small quantities and possession of larger quantities. As the first empirical assessment of awareness of a multi‐drug decriminalisation law in Australia, this research underscores the need for continued public messaging to improve understanding of the ACT's drug policy reform and to realise its intended public health benefits.

That said, the observed increase in awareness and partial understanding of the ACT's decriminalisation law indicate that some aspects of the reform have been communicated effectively. Among those aware of the legislation, most correctly recognised that it applied only to drug possession, not to sale or supply. Similarly, many understood that the way police could respond to small quantity possession offences had changed; however, while most participants correctly identified that police could issue a fine or a diversion notice, notable proportions also selected incorrect options—such as believing police would ‘do nothing (i.e., let me keep the drugs)’. Both populations showed a decline in the proportion who believed they could be arrested or jailed, suggesting recognition that decriminalisation reduces the risk of such outcomes, but also highlighting limited awareness of other contextual factors. These include program requirements (e.g., attending an AOD assessment to avoid being sent to court), circumstances in which people may still be charged with small quantity possession offences rather than issued a fine or diversion notice (e.g., when other offences are detected; [20]) and the ongoing role of police and judicial discretion [28, 29] in shaping outcomes.

There were also significant increases in the proportion of respondents who believed that possession of a larger quantity of drugs (e.g., 4 g of crystal methamphetamine) could lead to a magistrate issuing a good behaviour order, fine, or diversion to AOD treatment. While these are possible outcomes, they were already available prior to the reforms and it is therefore unclear what these increases represent. They may reflect a broader perception that all drug possession is now generally met with health‐based or lower‐level criminal justice responses; however, it is unclear whether respondents also recognised the full range and severity of penalties available through the courts for possession offences that exceed the small quantity threshold. Indeed, between one and two fifths of respondents did not identify imprisonment as a possible outcome, which may indicate an underestimation of the more severe penalties that can still apply. In practice, possession offences exceeding the small quantity threshold but below drug trafficking limits that proceed to court can still attract high fines (up to $8000), potential prison sentences of up to 6 months (albeit reduced from 2 years) and criminal convictions [20], while penalties for possession offences above the trafficking threshold remain unchanged.

These findings are broadly consistent with those that have been observed internationally following shifts in drug policy. In British Columbia, Canada, where a 3‐year pilot decriminalisation period commenced in January 2023 [30], surveys of people who use drugs prior to [22] and during the pilot period [23] revealed most were aware of decriminalisation policy, but misunderstood key details, specifically possession thresholds and included substances. During interviews, several respondents highlighted that their understanding of the specifics of decriminalisation stemmed from ‘word‐of‐mouth’ information from friends and other users, rather than official sources, which may have perpetuated misinformation [23]. Similarly, research from Tijuana, Mexico, found that only 11% of a sample of people who inject drugs were aware of decriminalisation reform 1–3 years following implementation, with respondents who were unaware of the changes more likely to undertake harmful practices such as needle sharing [31]. That is, poor legislative comprehension can undermine the potential public health benefits of decriminalisation.

In the context of the ACT's decriminalisation reform, mass media campaigns were implemented to promote understanding of the changes, with significant involvement from community organisations. ¹ However, despite these efforts, our findings suggest continued confusion persists, particularly around the distinction between decriminalisation and legalisation and what the reform means in practice for people who use drugs. This indicates that ongoing, sustained education efforts may be needed to clearly emphasise that possession remains illegal, even when addressed through administrative rather than criminal sanctions and to build trust through continued community partnerships that can tailor messaging to those most affected.

That said, the complexity of the legislation makes clear communication challenging. In addition to requiring knowledge of both the new ‘small quantity’ thresholds and the existing trafficking thresholds, the presence of pre‐existing diversion pathways adds another layer of ambiguity. Prior to the 2023 reform, the ACT already had a form of de facto decriminalisation for drugs other than cannabis, whereby individuals found in possession of any illicit drug could be issued a caution or diversion at the officer's discretion. As a result, it is likely difficult for people who use drugs to discern which outcomes reflect the new legislation and any associated changes in practices and which arise from longstanding policing practices. This complexity is further compounded by the selective inclusion of only some substances within the 2023 reforms—while drugs such as GHB and ketamine are excluded, they may still be subject to diversion under the pre‐existing de facto scheme. It is also possible that the apparent confusion between decriminalisation and legalisation stems not only from the short timeframe between the 2020 and 2023 reforms but also their differing legislative frameworks. Under the Drugs of Dependence (Personal Cannabis Use) Amendment Act 2019 [19], people in the ACT can legally possess up to 50 g of dried cannabis or 150 g of freshly harvested cannabis, with no subsequent legal intervention. In contrast, the Drugs of Dependence (Personal Use) Amendment Act 2022 only allows for fines or referral to a diversion program for small‐quantity possession of other illicit drugs in order to avoid criminal charge [20, 21]. There appears to be no clear justification for this discrepancy, which not only compounds the inconsistent and fragmented nature of drug policies in Australia [32], but also has the potential to create misunderstanding among people who use drugs. This confusion may be heightened by the fact that under federal law, possession of all these substances remains illegal, creating overlapping and potentially conflicting legal frameworks that people must navigate [33].

Given these complexities, simplification of the existing legislative model may warrant consideration. In particular, models that remove sanctions altogether may reduce the interpretive burden associated with navigating complex eligibility criteria and procedural requirements, while also minimising the legal consequences of misinterpretation and offering additional benefits. No‐sanctions models—where possession and use of illicit drugs do not attract criminal or civil penalties and engagement with health or support services is voluntary rather than mandated—may offer one such approach [6, 9]. International evidence indicates that, compared to decriminalisation models involving health sanctions, these approaches, when applied across all illicit drugs, can yield health, social and economic benefits without placing additional demands on frontline services or people who use drugs [9]. Such approaches are also preferred by the International Network of People who use Drugs [34]. Regardless of the model, future reforms should also consider incorporating additional substances such as GHB and ketamine as eligible for legislated diversion, or extending the approach across all illicit drugs. Such changes could help better align the drug law reforms with their intended health and social benefits, while also improving legal clarity for people who use drugs.