The ins and outs of cannabis legalisation … Proposals from Greens senator David Shoebridge … Constitutional possibilities … Forget the states … Let the Commonwealth light-up … External affairs … Patents … Referral powers … Max Shanahan takes a puff 

When you lag behind Missouri in progressive law reform, something has clearly gone awry. 

Public and expert opinion lies overwhelmingly behind the legalisation of cannabis for recreational use, yet the greatest impediment to the achievement of law reform is not intransigent politicians, but rather structural features of Australia’s constitutional system. 

A new proposal by Greens Senator David Shoebridge postulates that Australia’s cannabis conundrum may be solved by the novel use of existing Commonwealth heads of power to legalise recreational cannabis on a national scale. 

Brandishing legal advice from Professor Patrick Keyzer, Dean of the ACU Law School, the Greens argue that any or all of the territories, external affairs and patents powers could form the basis of new cannabis legislation, usually the preserve of state and territory parliaments. 

Constitutionally, the self-interest of states and territories is the main impediment to achieving legalised recreational cannabis. 

As Kezyer notes in a 2020 article, section 90 of the Constitution gives the Commonwealth exclusive power to levy taxes on goods, while the states retain the power to legislate on the legalisation or decriminalisation of cannabis and drug use, production and supply broadly.

“What incentive does a state have to decriminalise cannabis if they cannot tax it?”

Therefore, even if a state was minded to legalise or decriminalise cannabis use, it would be unable to raise revenue without entering into some sort of agreement between other states and territories and the Commonwealth. 

With no fiscal incentive to do so, it is unlikely that any state or territory government will follow the ACT in relaxing laws on cannabis use. 

A further non-constitutional barrier, Shoebridge argues, is the “law n’ order” culture that pervades state politics across much of the country. Pursuing cannabis legislation at a Commonwealth level has the great advantage, he says, of “stepping away from that toxic law and order politics at the state level”, particularly the entrenched influence of state police on policymaking. 

To achieve meaningful law reform on cannabis, revenue raising and legislative powers need to be combined. Except by some extraordinary constitutional gymnastics by which a state might impose a fee “specifically hypothethicated” to addressing the effects of cannabis use, it is unlikely that the states can exploit any revenue raising power. 

Legalisation of cannabis through Commonwealth heads of power emerges as the most effective and realistic means of achieving law reform. Keyzer proposes three heads of power which could sustain cannabis legislation. 

Territories Power

The ACT decriminalised recreational low-level cannabis possession and production in 2019. Keyzer argues that the Greens could develop and pass legislation adopting the ACT model – or indeed any other model – using the section 122 plenary power. 

The Commonwealth may then invite the states to join in a uniform scheme and pass matching legislation, with a concomitant agreement on revenue sharing from the taxes the Commonwealth would levy on cannabis sales and production. 

Alternately, as Professor George Williams from UNSW told Justinian, if the states are on board, the section 51(xxxvii) referral power would allow the Commonwealth to legislate for any or all of the states if their parliaments choose to refer the matter to Canberra. 

As Keyzer says, “having state and territory sign-up is critical”. 

Such cooperative methods would be the smoothest and most effective method of cannabis law reform, avoiding the need for more complex and controversial constitutional formulations. 

However, with the NSW parliament dragging its heels on minor cannabis law changes, such extensive cooperation appears to be something of a pipe dream in present circumstances. 

External Affairs

If state cooperation is unlikely to be forthcoming, then a legislative scheme relying on a new interpretation of Australia’s international obligations could find success. 

The relevant instrument which may bring cannabis legislation within power is the 1961 Single Convention on Narcotic Drugs, to which Australia is a party. 

The Convention “seeks to limit the possession, use, trade, distribution … and production of drugs exclusively to medical and scientific purposes”. 

The Commonwealth has already leant on the convention to relax cannabis laws, invoking it in its 2016 legislation legalising medical marijuana. 

While the Convention might initially seem to limit opportunities for non-medical legalisation, Canada’s novel interpretation of the instrument to legalise cannabis use shows how international instruments may be permissive rather than restrictive in this field. 

The stated purpose of Canada’s Cannabis Act attempts to accord with the provisions of the convention. By regulating cannabis production and supply, the Act purports to “restrict access to cannabis” and “reduce illicit activities in relation to cannabis” while providing “quality-control” and “enhancing public awareness of the health risks associated with cannabis use”. 

Therefore, by restricting the black market, the Canadian legislation purports to be protecting health by restricting access to cannabis through regulation rather than criminalisation – seemingly in accord with the Convention. 

Indeed, the Canadian taskforce on cannabis legalisation and regulation reported that: 

A similar argument has been made to support the compatibility of safe injecting rooms with countries’ international obligations. 

However, Canada’s approach has failed to convince all, with many believing the Cannabis Act simply ignores the provisions of the Single Convention. For example, Hoffman and Habibi, writing in the Canadian Medical Association Journal, contend that the legislation “almost certainly violates Canada’s international obligations”. 

Regardless of whether the creative reinterpretation of the Convention to support legalisation is entirely correct, so long as, per Deane J’s test in Tasmanian Dams, any putative legislation is capable of being reasonably considered to be appropriate and adapted to implementing the treaty obligation, then it will fall within the external affairs power. 

However, it would likely take a very permissive court to permit such an interpretation. In addition, such a move – in the unlikely event a major party supports it – is unlikely to be looked upon kindly by the international community. 

The International Narcotics Control Board, which monitors the Single Convention, publicly argued that the ACT’s small-scale decriminalisaton of cannabis was “inconsistent with Australia’s international legal obligations“. 

Patents Power

The final potential constitutional provision which could permit Commonwealth legalisation is the s.51(xviii) patents power. Keyzer explains further:

“Section 51(xviii) includes patents of inventions, which since the 1950s has included what the Europeans call plant variety rights … If you took that approach, you could have a register of cannabis plant varieties …” in respect of which the Commonwealth has exclusive regulatory control. 

This method appears to be preferred by the Greens. Shoebridge tells Justinian that the patents powers “is a convenient way of legalising cannabis [and] the benefit of using the patents power is that it has already been fully ventilated in a fairly recent constitutional challenge and been upheld by the High Court”. 

That case, Grain Pool of WA v Commonwealth upheld legislation on plant variety rights as a valid exercise of the patent power. 

While s. 51(xviii) appears to be the most realistic head of power, as Keyzer says, “as long as the Commonwealth and the states agree, then you can do anything”. 

The greatest barrier to nationwide legalisation might not be finding valid constitutional support, but rather securing the support of the states and territories to radically depart from their existing policies. 

Uncooperative states would likely kill any putative federal scheme. Professor Peter Gerangelos speculates that, even if s.51(xviii) were to be successfully used, intransigent states could still prohibit cannabis use and get around s.92 problems by relying on the Castlemaine exception to regulate intrastate trade in the plant by characterising it as a threat and making laws that are appropriate and adapted to protect from that threat. 

With a complex and largely untested constitutional framework, reluctant states and no major party support, this push for cannabis legalisation won’t succeed. 

However, in raising the prospect of federal legislation in this area, the Greens have opened a new front in drug reform – one which will play an important role in a drawn out process. 

Senator David Shoebridge already notes a significant change in attitude towards cannabis legalisation from the two major parties: 

“What has been somewhat surprising has been the absence of active political opposition from the right or from the Labor Party. If we’d launched this campaign 10 years ago, there would have been angry denouncements from the right of politics, alleging that the Greens were all in some sort of drug-induced stupor. 

But in this instance they have been silent. They know that opposing legalising cannabis is politically toxic for them. When it comes to the Labor Party, their primary response has been to de-escalate and say they don’t have any current plans.”

Beginning a conversation about the potential for federal cannabis legalisation and the muted response of the major parties are signs that cannabis legalisation may have promising future prospects. 

With a large majority of Australians supporting some form of decriminalisation or legalisation, and academic opinion similarly in favour, constitutional cannabis may no longer be a pipe dream.