US Marijuana Law and its International Legal Implications

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In the U.S., cannabis law is a confusing mess of federal and state regulations, medicinal and adult use standards, and complex consequences for those involved in the industry. Marijuana is federally illegal, but 24 states and Washington D.C. have legalized adult recreational use of marijuana and 14 more have legalized medicinal use.[1] Considering the political environment around marijuana legalization, it is likely only a matter of time until marijuana is decriminalized or legalized for recreational use in the U.S. While this change would relieve much of the dysfunction of America’s marijuana industry, it could also lead to scrutiny against the U.S. for violating international conventions.

Under the United Nations 1961 Single Convention on Narcotic Drugs, signatories agreed to exclusively allow medical and scientific uses of the listed drugs, including marijuana.[2] This includes the production, export, import, distribution of, trade in, and possession of marijuana.[3] This Convention also created the International Narcotics Control Board, a quasi-judicial body which is responsible for monitoring and supporting signatory countries’ compliance with the international drug treaties.[4] Under the plain language of the convention, federal legalization of adult use marijuana would violate this commitment, and the International Narcotics Control Board has already voiced their disapproval of the U.S. federal government’s decision to allow the states to legalize adult use.[5]

International law certainly influences national and local laws through good faith compliance, but the bigger and more applicable question here is whether international law can influence a national government enough to refuse their citizens popular policy changes. This is entirely dependent upon the consequences the country would face if they were to violate the international law.

Uruguay and Canada, who are also signees to the Convention, have legalized adult use and have faced no more than statements from the INCB stating their disapproval for the action.[6] In 2023, the INCB released a statement expressing “concern over the trend to legalize non-medical use of cannabis,” but this statement neglected to articulate judicial or punitive measures which would be taken if more signatories legalize cannabis for adult use.[7] As the Convention does not provide a direct enforcement mechanism, it has left the INCB’s threats to be largely toothless in the face of developing global policy.[8]

When the time comes, the US federal government will need to determine how to handle the INCB and their clear disapproval for adult use marijuana legalization. Assuming that American policy will eventually turn in favor of adult use regulation, the U.S. has two clear options: 1) knowingly violate international law or 2) attempt to lead the charge in amending the Convention. Violating international law may not have serious consequences from the INCB or fellow nations who are also looking to legalize marijuana for adult use, but it does set a precedent which could be negatively impactful in the future. The United States has a unique role on the international stage, and with this influence comes a level of responsibility. If the United States disregards commitments it has previously made, then that has the potential to not only undermine the international influence the U.S. has accumulated, but it also has the potential to encourage other nations to do the same. The U.S. has an interest in maintaining the credibility of international law, and such blatant disregard for an international convention could negatively impact this interest.

Amending the Convention is possible under Article 47, but the process is arduous, and the US would likely need to push for this change to occur.[9] The Single Convention on Narcotic Drugs requires a uniquely difficult process to enact an amendment and somehow, international affairs move more slowly than domestic U.S. affairs.[10] There is a way to modify the substances list to move marijuana to a less-restricted category which could ease pressure in the event of a domestic U.S. policy change, but this would not eliminate the legal conflict entirely. In 2020, the Commission on Narcotic Drugs moved cannabis from schedule IV (the most restricted category) to schedule I, which loosens control on it but still does not allow for recreational use.[11]  

If the United States chooses to legalize or de-schedule marijuana on a federal level, the international community, namely the INCB, will expect the U.S. to address its international obligations under the Single Convention on Narcotic Drugs. If the U.S. began efforts to amend the Convention now, then this could be completed by the time the federal government comes around to legalization, but this is unlikely to be a domestic priority any time soon. If the U.S. declines to decriminalize marijuana on a federal level and allows a complex, often discriminatory system of laws to continue, then it is fair for marijuana legalization advocates to ask, “is compliance with this convention worth the sacrifice?”

[1] Athena Chapekis and Sono Shah, Most Americans now live in a legal marijuana state – and most have at least one dispensary in their county, Pew Research (Feb 24, 2024),

[2] Single Convention of Narcotic Drugs, art. 4 & 28, opened for adoption Jan. 24, 1961, 975 U.N.T.S. 105.

[3] Id art. 4.  

[4] Id art. 5.  

[5] Blickman et al., Willful Blindness: The INCB Can Find Nothing Good to Say on Cannabis Legalization, Transnational Inst. (Mar. 14, 2024),

[6] Press Release, International Narcotics Control Board, The International Narcotics Control Board on the Entry into Force of Bill C-45 Legalising Cannabis for Non-Medical Purposes in Canada, UNIS/NAR/1362 (Oct. 17, 2018),by%20the%201972%20Protocol%2C%20according.

[7] See Press Release, International Narcotics Control Board, The International Narcotics Control Board Expresses Concern over the Trend to Legalise non-Medical Use of Cannabis, Which Contravenes the 1961 Single Convention on Narcotic Drugs, UNIS/NAR/1496 (Mar. 9, 2023),–which-contravenes-the-1961-single-convention-on-narcotic-drugs.html.

[8] See Single Convention of Narcotic Drugs supra note 2.

[9] Id art. 47-48.

[10] Aparna Bushan, Note: An Evaluation of the Effects of the Legalization of Marijuana in Colorado and Washington from an International Law Perspective, 39 Canada-U.S. L. J. 187, 200-01 (2015).

[11] Id.