On Oct. 17, when Canada becomes the first G7 nation to legalize recreational marijuana, this is how it will go at the US border: If you’ve legally used marijuana, or have participated in any aspect of its booming legal cannabis sector, you could be slapped with a lifetime travel ban.

According to Politico, which first reported the story, the US Customs and Border Protection (CBP) agency said that those working or investing in the marijuana industry will be treated as drug traffickers. According to the Vancouver Star, high-profile investors, including venture capitalist Sam Znaimer, have already been banned from the US for life because of their involvement in legal Canadian cannabis operations.

While recreational users will not be specifically targeted, they could face the same penalty:

“Our officers are not going to be asking everyone whether they have used marijuana, but if other questions lead there — or if there is a smell coming from the car, they might ask,” the CBP’s Todd Owen told Politico. “If you lie about it, that’s fraud and misrepresentation, which carries a lifetime ban,” Owen said.

If travelers admit to having used any drugs that are illegal in the US—including marijuana, which is federally prohibited even though many states allow it—they would also be barred from entry unless they obtain a waiver at the CBP’s discretion.

The policy is actually a longstanding protocol under the US Controlled Substances Act, but Owen, executive assistant commissioner for the CBP’s Office of Field Operations, said that secondary inspections by the US Customs and Border Protection agency will increase once Canada legalizes weed.

Even simply investing in Canada’s weed could be grounds for a travel ban, because it counts as participating in an illegal business. But what US federal authorities must categorize as an illegal business is also a thriving industry, and thousands of Canadians own cannabis shares on the Toronto Stock Exchange. By 2022, Canada’s cannabis industry is expected to generate $5.4 billion for both the recreational and medical markets, and big corporations have already started making major investments.