Jordan Sinclair, with Canopy Growth, a major medical marijuana supplier in Canada, told the BBC that while their employees have yet to face difficulties at the US-Canada border, the industry as a whole is seeking more clarity as to how cases will be consistently handled by border officials.
While almost all border states have some form of legalized marijuana use, it remains illegal under USA federal law, which classifies those who work in the marijuana industry as drug traffickers.
Owen said U.S. Customs and Border Protection will apply existing laws against admitting drug users and drug traffickers into the United States.
"Canadians are going to let their guard down and think what's the problem", says Todd Owen, executive assistant director for the Office of Field Operations for U.S. Customs and Border Protection Agency.
Owen also said Canadians who tell border agents they work in the marijuana industry risk not being permitted to enter the country.
Also, marijuana residue - which can linger inside of a vehicle - could possibly be detected by inspection dogs and lead to further questioning. Owen said if travelers lie about past drug use during questioning, that's "fraud and misrepresentation, which carries a lifetime ban".More news: Nicki Minaj and Cardi B’s feud is spilling over into politics?
"Facilitating the proliferation of the legal marijuana industry in USA states where it is deemed legal or Canada may affect an individual's admissibility to the U.S".
Typically, travellers will be given the opportunity to "voluntary withdraw" from the border, or they face an "expedited removal".
While admitting to illegal drug use will make you inadmissible, one can also apply for a waiver from the lifetime ban, but it will cost US$585 and can take several months to process.
He added that rather than lie at the border it is better to not respond to the questions.
And now, Canadians who work in the marijuana industry will not be permitted to enter the US.
Owen told online news outlet Politico that the USA will continue to enforce its prohibition come Oct 17, when recreational Cannabis becomes legal.More news: Israeli army destroys huts built to oppose demolition of Khan al Ahmar
Prime Minister Justin Trudeau's government officials have maintained that despite the change in law, there is no indication marijuana legalisation will shift the U.S. approach in how it deals with Canadians crossing the boundary, and confirmed that involvement in the industry could result in denied entry.
"Every country has the right to judge who gets to come into their borders or not", he said.
"If you work for the industry, that is grounds for inadmissibility", Owen told Politico.
"I certainly won't work to assume or impress upon the USA who they have to let in or not".
Eight US states - Colorado, Washington, Oregon, Alaska, Maine, Massachusetts, Nevada and California - have now legalised recreational and medicinal marijuana.More news: US anger at Russia changes to UN N.Korea report