A briefing note obtained by the Canadian Press reveals that Justin Trudeau’s Liberal government will need to deal with several international treaties before the country is able to legalize cannabis.

Canada’s participation in the Single Convention on Narcotic Drugs of 1961, as amended by the 1972 Protocol; the Convention on Psychotropic Substances of 1971; and the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances of 1988 will all need to be amended before the prime minister’s promise to regulate recreational cannabis can take effect.

The international element complicates an already murky path for legalization that includes working with provincial and federal bodies including law enforcement and the judiciary.

University of Ottawa constitutional and international law expert Errol Mendes said the process will take longer than many expect.

“It will be an ongoing dialogue which has to be dealt with at the highest levels, and it’s not going to be an easy one, and it’s not going to be a quick one either,” said Mendes. “It’s going to take many years.”

In a Facebook post on the topic, B.C. lawyer Kirk Tousaw said the issue over international obligations isn’t anything that should slow the government’s plans.

“The MMPR does not comply with the treaties either,” Tousaw said, referencing the federal medical marijuana program created by the previous conservative government. “This is much ado about nothing. Withdraw or ignore them.”

Mendes said all three of the treaties require participant nations to criminalize cannabis cultivation and distribution and Canada will need to explain to the international community why it will renege on its commitments.

A special session of the United Nations General Assembly in April looks to focus on the world’s drug issues, with some nations expected to open the debate on the renegotiation of existing policies.

According to Mendes, Canada could still adhere to the existing treaties but will need to show how legalizing cannabis will reduce its use.

“The problem is the government having to explain why it’s doing it, why it feels it has to do it, given the conviction [with which] Prime Minister Trudeau has said it’s a failure in terms of enforcement in almost every respect and is driving up the crime rate in some parts of Canada,” Mendes said.