Opposition parties and legal experts are urging the Liberal government to be clear on how it plans to handle the legalization of cannabis while Canada remains party to three UN treaties that control and criminalize drug access, noting failure to provide clarity soon could cause confusion on the world stage.

Canada needed to give notice on July 1 if it intended to withdraw from the treaties and stick to its plan to legalize marijuana by this time next year, said Steven Hoffman, a York University professor who specializes in global health law.

It didn't, and Hoffman said he is concerned about the message this sends.

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"The lack of clarity around how the federal government is going to address its international legal obligations under the UN drug control treaties is concerning given it sends the message to countries around the world ... that our international law obligations are not at the forefront of our minds," Hoffman said.

"Canada is one of the world's leading countries, a member of the G7, a country that everyone looks up to ... what we do and the consequences of us violating international law are very different than the consequences of other countries ... it is a big deal if Canada breaks international law."

Canada is currently one of more than 185 parties to three United Nations drug-control conventions — the 1961 Single Convention on Narcotic Drugs, the 1971 Convention on Psychotropic Substances and the 1988 Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances.

Documents obtained early last year by The Canadian Press detailed how all three treaties require the criminalization of possession and production of cannabis, noting Canada must explore how to inform the international community of its plans to legalize marijuana and review steps to adjust obligations under these conventions.

The federal government is examining a range of issues related to the legalization of cannabis, including international commitments, said a spokesperson for Foreign Affairs Minister Chrystia Freeland.

"We are committed to working with our global partners to best promote public health and combat illicit drug trafficking," Adam Austen said in a statement.

But NDP health critic Don Davies said Freeland is failing to acknowledge the government will no longer be in compliance with the treaties once cannabis gets the legal green light.

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"I think it is the norm in our country to respect those agreements and to make sure we are in compliance so the only responsible course of action would have been to notify the UN of our intention to withdraw from those treaties," he said.

Canadians expect a clearer, more responsible approach from Ottawa on the legalization of marijuana, he added.

Conservative foreign affairs critic Peter Kent said these decisions should have been made public weeks ago.

"We encourage our international partners — democracies and non-democracies — to respect treaties to the letter," Kent said in an interview.

"If Canada, for whatever reason, finds itself in violation, that is a sad day."