Al Larocque says he's always been truthful when crossing the border.

But if the Fruitvale, B.C., resident is asked by U.S. border agents if he's ever smoked marijuana, he knows what he's going to do.

"I'm going to lie," he said Tuesday.

Larocque lives just north of B.C.'s border with Washington state, a boundary he crosses several times a year to reach his winter home in Arizona.​

But a report Monday — about Estevan, Sask., residents being refused entry into North Dakota after admitting to past cannabis use — has Larocque spooked about his next southbound trip next month.

"I don't want to lie. And I'm going to lie. And that is unfortunate. Because I am a truthful person and I think most Canadians are," he said.

Larocque is worried about getting cut off from his second home.

Still, he should rethink his plan, say lawyers consulted by CBC News.

"Do not do that. Trust me," said Henry Chang, a partner at the Toronto law firm Blaney McMurtry LLP who specializes in immigration law and practises in both Ontario and California.

The repercussions of being caught lying to a U.S. border agent outweigh the potential gain of fibbing without detection, Chang said — namely, you could be permanently banned from entering the U.S.

'People don't understand' the rules: lawyer

There are two other things that could get you banned from the U.S. in the post-Canadian legalization age, according to Chang.

The first is a prior conviction for marijuana possession.

The second is admitting to having used marijuana before its recreational use was legalized by the Canadian government on Oct. 17.

Henry Chang, an immigration lawyer based in Toronto, says people can refuse to answer the question and seek American legal advice in the meantime. (Blaney McMurtry LLP)

"If you say, 'Yeah, I smoked marijuana when I was 18, but it's not a problem, right?' — it is problem. You are barred for life, as if you had been convicted back then. People don't understand that," said Chang.

"Legalization doesn't cure prior problems," he added.

Medical marijuana users with a valid prescription who admit to using the drug won't be banned, Chang said, though they still can't import any marijuana into the U.S.

What about recreational users who admit to doing marijuana after it was legalized?

"It's not as black and white," said Chang.

If it was a one-time tryout by a curious newbie involving cannabis bought from a legal Canadian seller, "you should be OK," he said.

Medically examined for signs of addiction

But a person who admits to using cannabis repeatedly could still be barred from entering the United States, said Chang.

"If they conclude that you're a drug abuser [or addict], you're barred [on] that ground, separate and apart from whether it's legal or not."

That conclusion can't be reached, however, until a Canadian panel physician approved by U.S. Customs and Border Protection (CBP) examines someone following a detention.

"You will be temporarily banned until you get the medical exam done," said Chang, adding that the findings are shared directly with CBP, not with the patient.

"If they tell you [at your next border trip] you're not getting in, you know what the medical exam said," he said.

People barred on this ground aren't necessarily banned for life, however, thanks to what Chang called a "remission provision." The panel physician (either in Vancouver, Toronto or elsewhere) may re-examine someone and find they no longer meet the definition of addict or abuser.

"But it can bar someone for several years until they have proven that they no longer use drugs, including legal cannabis," said Chang.

Andrew Mason, a Saskatoon defence lawyer, said people with past convictions for pot possession can obtain a waiver but it's a costly and 'cumbersome' process. (CBC)

People with a prior pot possession conviction have an option too.

They can apply to U.S. Citizenship and Immigration Services for a waiver (form I-192) that would essentially see the U.S. government overlook a past offence.

People have to provide a criminal record check and references, pay a $1,200 Cdn fee and periodically get their waiver renewed.

"It's a cumbersome process," said Andrew Mason, a Saskatoon-based defence lawyer.

And it's not to be confused with a pardon from the Canadian government, which may not do any good anyway, Mason added.

"It doesn't erase the fact that you had committed the offence in the past."

Their advice? Delay

Given all these strict rules, what should marijuana users do when questioned by border agents?

"That's a question I get a lot," said Chang. "It's a no-win situation for anyone who gets asked the question.

"If you admit to using controlled substances prior to legalization, you are barred," he continued. "If you lie and say you've never smoked it and they find out, it's a permanent bar for material misrepresentation, which is also quite serious."

Chang and Mason agree it's better to take a take a third, if imperfect, approach.

Delay.

"Refuse to answer the question. Say it's irrelevant. Say you don't know why this question is being asked," said Chang.

It won't get people to their destinations — and they'll merely be confronted with the same question next time — but at least they can consult a lawyer, he said.

That lawyer may even be able to resolve the situation directly with CBP "without you having to make an actual admission," said Chang.

"Because once you've admitted it, it's done. You're barred. Nothing anybody can do except apply for a waiver."

A diplomatic solution

Mason is hopeful another solution can be worked out.

"I expect the governments of Canada and the U.S will get together and make it so that most people who have smoked it in the past but who are not likely to break U.S. drug laws will not be disallowed in the United States.

"But that's going to take a bit of negotiation and discussion."