Advance Blog

March 2, 2023
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Thailand’s Cannabis Treaty Obligations: Conventions and Constraints

1           Introduction and Overview

The issue of compliance with international law and conventions is an important consideration when discussing Thailand’s cannabis law reforms. The United Nations 1961 Single Convention on Narcotic Drugs (the “Single Convention”) is the primary international legal instrument that regulates the use of cannabis as well as other narcotic drugs.

The Single Convention classifies cannabis as a Schedule 1 substance along with cocaine, fentanyl, heroin, methamphetamines, and morphine (to name a few of the other Schedule 1 drugs), which means that cannabis may be subject to draconian controls under the Single Convention. The Single Convention also, according to most writers, requires that signatory countries criminalize the cultivation, production, and distribution of cannabis for non-medical purposes.

However, there is considerable debate as to whether the Single Convention does prohibit non-medical uses of cannabis. The author argues that the Single Convention’s wording is open to interpretation and that Thailand can legalize cannabis for non-medical use without violating its obligations under the Single Convention and the 1988 Convention.

While Thailand has been engaging in cannabis policy reforms, there is also profound hypocrisy in Asia that underscores the importance and political relevance of reconciling treaty obligations with domestic cannabis reform.

Ultimately, the legality of Thailand’s cannabis law reforms will depend on the specific legal framework that is implemented. If the regulations are designed in a way that complies with the various treaties’ requirements and the broader principles of international law, then Thailand can legalize cannabis for non-medical use without violating international law and these treaty responsibilities.

Thailand’s official objective in decriminalizing cannabis was to gain an early advantage over neighboring countries in capturing a significant share of the highly profitable market for health treatments that employ cannabis derivatives, with a particular emphasis on the less potent compound known as CBD. However, an additional motivation behind this move was to alleviate overcrowding in some of the world’s most densely populated prisons where 1 in 10 prisoners was arrested for cannabis or cannabis-connected offences.

Whilst the Thai government publicly stated it was permitting the production and consumption of cannabis for medical purposes and limited personal use, it did so without a regulatory framework in place to ensure that the production and distribution of cannabis remain strictly for medical or personal purposes. This framework could have included measures to prevent the diversion of medical cannabis into the recreational market as well as limitations on personal use. These measures are often simply known as “track and trace” regulations.

At present, it is difficult to draw a clear line between medical and recreational cannabis use in Thailand as licenses issued under the Traditional Medicine Act[1] allude to therapeutic sales but there are no mechanisms in place to ensure this outcome.

2           Thailand and International Treaties

In the Single Convention and the 1988 Convention, “decriminalization” refers to personal activities which are unauthorized or illicit but upon which no sanctions or penalties are applied. “Personal activity” is a term used to refer to an individual’s personal or private actions, behaviors, or conduct, that are typically not intended to affect or harm others. The term is often used to distinguish between activities that are considered private and those that are subject to regulation or restrictions imposed by law or public policy.

2.1      The 1961 Single Convention:

  • Article 33 permits the possession of cannabis “under legal authority.”
  • Article 36(1)(a) mandates that Parties penalize all activities … “subject to [the] constitutional limitations” of each Party.
  • Article 36(1)(b) allows Parties to apply a specific health-centered alternative to conviction/punishment, such as “treatment, education, after-care, rehabilitation, and social reintegration,” if those who commit an offence are “abusers of drugs.”

The Single Convention, therefore, does not require penalization of personal activities. The Convention’s Commentary[2] reinforces this and states that countries may “choose not to impose penalties on the unauthorized possession for personal use”.

2.2      The 1988 Convention[3]:

The 1988 Convention simply adds provisions to activities that were already considered illicit under the 1961 and 1971 conventions.

The 1988 Convention includes specific provisions related to cannabis.

  • Article 3(1)(a)(ii) requires Parties to criminalize the cultivation of cannabis plants that are “contrary to the provisions of the Single Convention” under their domestic law.
  • Article 3(2) allows Parties to establish measures that make the “possession, purchase, or cultivation of narcotic drugs […] for personal consumption” a criminal offence only if it conflicts with their constitution or legal system’s fundamental concepts, relieving them of the Article’s obligation to penalize drug possession and cultivation for “personal consumption.”

Thailand, for example, probably relied on Article 3(2) of the 1988 Convention in its decision to decriminalize conduct involving personal consumption.

  • Article 3(4)(c) permits Parties to provide alternatives to conviction or punishment, such as education, rehabilitation, or social reintegration, as well as treatment and aftercare when the offender is a drug abuser, in appropriate cases of minor nature.
  • Article 3(4)(d) allows Parties to provide measures for the treatment, education, aftercare, rehabilitation, or social reintegration of the offender as an alternative to conviction or punishment or in addition to them.

2.3      Thailand’s Treaty Options

Other than pure THC extracts and illegal activities, cannabis is not regulated at all by the 1971 or 1988 Conventions. The regulation of cannabis is therefore primarily established by the Single Convention.

The Single Convention’s stated goals are;

“To safeguard the health and welfare of humankind through two overarching goals, namely: (a) ensuring the availability of controlled narcotic drugs and psychotropic substances for medical and scientific purposes and ensuring the availability of precursor chemicals for legitimate industrial use, and (b) preventing the diversion of controlled substances into illicit channels.”[4]

According to some, the Single Convention aims to prohibit all non-medical and non-scientific uses of drugs. However, this position is hard to reconcile with the actual words of the Single Convention. The Single Convention only mentions the “option to prohibit” and as being discretionary for the parties involved. The Single Convention, therefore, considers prohibition a legitimate legal option, but not an obligation.

Additionally, the restriction on cannabis use for medical and scientific purposes is not entirely rigid. Within this limitation, there are several exceptions and exemptions.

By putting cannabis under the Traditional Medicine Act, Thailand has taken a path for the direct regulation of a “non-medical (cannabis) industry”.

The implementation of this option does not necessitate any alterations to the treaties or changes in Thailand’s ratification of these conventions. Instead, it involves the development of Thailand’s national regulations following the provisions of Articles 2 (9) and 28 of the Single Convention.

This option construes the restriction on the use of controlled substances for medical and scientific purposes in Article 4(c) of the Single Convention as being flexible and allowing for local decision-making on what is possible for non-medical and non-scientific purposes. Article 2(9) plays a crucial role in this option as it specifies that:

“Parties are not required to apply the provisions of this Convention to drugs which are commonly used …. for other than medical or scientific purposes, provided that:

a) They ensure …. that the drugs …. are not liable to be abused ….”

Applying the general principles of treaty interpretation, it is possible to draw a connection between the industrial, non-medical, and non-scientific objectives outlined in Article 2(9) of the Convention and the current Thai cannabis industry. This interpretation gives full effect to the provision, as long as the cannabis industry in question contributes to the betterment of human health and well-being. The nexus and legitimacy provided by signaling a relationship with the Traditional Medicine Act are obvious.

As long as the obligations outlined above are fulfilled, the establishment of a non-medical cannabis industry under Article 2(9) would not contravene the provisions of the Single Convention, nor those restrictions stated in the 1988 Convention. Furthermore, the concept of permitting “possession under legal authority” (Article 33 – Single Convention) means possession of cannabis obtained through a lawful non-medical cannabis industry would be permissible under the Single Convention.

Using the same principles of interpretation, the similarity between the term “industry” in Article 2(9) and “industrial” in Article 28(2) suggests that, for policy coherence and good faith comparison, cultivation can be sanctioned along with sales by way of interpretation of Article 2(9).

This interpretation is a straightforward choice that carries minimal risks. It can be put into action unilaterally and without delay and is the only alternative that enables compliance with the Single Convention and the 1988 Convention, utilizing established principles of international law.

About Dr. Paul Crosio and Silk Legal

Dr. Paul Crosio is a partner at Silk Legal and a founding partner at Silk Advisory. He is an Australian lawyer with 25 years of experience in Australia and Asia advising such firms as Citibank, WorldCom, Telstra International, and several others. He specializes in corporate matters, restructuring and corporate administration, as well as cannabis.

Silk Legal is a boutique law firm that focuses on complex legal matters in Thailand. We are a full-service commercial law firm with dedicated areas in corporate and commercial, restructuring, and insolvency, mergers and acquisitions, and regulatory matters. For more information, please visit our website at


1999 (The “Traditional Medicine Act” or “TMA”)

[2] UN Commentary of the Single Convention, 1973

[3] UN Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, 1990 (The “1988 Convention”)

[4] International Narcotics Control Board Annual Report 2022, p.15

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