All Australian states and territories have adopted legal threshold quantities for drug trafficking, over which possession of an illicit drug is deemed “trafficking” as opposed to “personal use”. Yet, the capacity of these thresholds to deliver proportional, equitable and just sanctioning of drug offenders, including the capacity to appropriately distinguish drug users from traffickers, has been rarely examined. In 2010 Hughes and Ritter put forward the first set of evidence-informed metrics for evaluating drug trafficking threshold design. Application to one Australian setting (the Australian Capital Territory) showed that the thresholds placed some users at risk of unjustified charge and conviction for trafficking. In this study we extended the previous analysis to evaluate and compare and contrast the trafficable thresholds throughout six Australian states: NSW, Victoria, Queensland, South Australia, Tasmania and Western Australia. For each state we evaluated the applicable trafficable threshold quantity against two metrics of the quantity of a drug that a user is likely to possess for personal use alone: using Australian data on patterns of use and purchasing. Doing so showed that most users are at minimal risk of exceeding the trafficable thresholds when they follow typical use and purchase patterns. On the other hand particular groups of users are at much greater risk of an erroneous charge as a trafficker (most notably users of MDMA and users in NSW and SA) for personal use alone. For example, in some states and some circumstances 80% of MDMA users possess more than the current threshold for their personal use alone. Moreover, we show that the risks in such circumstances are exacerbated by the idiosyncratic Australian criminal justice response to drug traffickers which removes the normal criminal justice safeguard concerned with burden of proof. This provides evidence that consistent with the results from the ACT the Australian system of drug trafficking thresholds are by their very nature imbued with the potential for unjustified or inequitable sanction. Equally importantly it shows that the level of risk can be mitigated by better design. We thus conclude by outlining possible ways forward include legislative reforms to elevate threshold quantities for some drugs/states.