The Canadian government will be in a better position to push for the U.S. not to ban entry to Canadian citizens who admit to smoking cannabis when questioned by border guards after recreational consumption becomes legal in Canada, according to an immigration lawyer.

But in the meantime, he said Canadians undergoing preclearance at Canadian airports will be in a “weaker position” than those driving to the states because they can be compelled to answer questions at preclearance, and can’t just turn around and go home.

Lorne Waldman, an immigration lawyer, told senators at the national security and defence committee Monday the Canadian government would be more persuasive on cannabis-related border-crossing issues with the U.S. after weed becomes legal.

He said that’s because Canada will then have “moral authority” to assert claims about Canadians being banned over consuming a legal substance.

Waldman said it is “much more difficult now to make that approach,” but the government still needs to actively petition the U.S. that it is not “appropriate” to ban Canadians for life over legal pot consumption.

“It’s something [the government] can and should do, and I hope they will do it before the law passes,” he said.

That’s because, even though the U.S. doesn’t officially seek out pot smokers to ban in their questioning, it’s clear that there are a few officials legally entitled to ask the question that do.

When Sen. Mobina Jaffer asked about how the Liberal government’s preclearance bill — passed by Parliament last year — comes into play regarding cannabis, Waldman said any advice to refuse to answer border guards “won’t apply at Canadian airports” when going through preclearance.

“It’s a bit strange that a Canadian on Canadian soil will be in a weaker position than a Canadian who drives across the border and is on U.S. soil.”

“People will now be compellable,” he said.

“I don’t think that, at the time the bill was passed, the drafters of the legislation really contemplated these types of situations. And I think it’s a big problem and exposes some Canadians to a vulnerable position for sure.”

Public Safety Minister Ralph Goodale told senators he is in frequent, “ongoing” conversations with U.S. counterparts about legalization, and it “comes up in virtually every conversation” he has with the U.S. secretary of homeland security.

Goodale told senators the main concern the Americans have put forward on pot is whether it will lead to lineups that could cause congestion at border points.

“Our message to the Americans is: this should not be an issue.”

“It becomes an issue if you make it one. And there’s no need to make it one because the border rules have not changed.”

He said there is no reason to change the questionnaire, or ask questions out of the blue “about conduct 15 or 20 years ago,” which is irrelevant to border security today.

But Canadians should also be “acutely aware” that U.S. law hasn’t changed.

He said Canadians “should not play fast-and-loose with border procedures” and realize that “at the border, the law changes.”

“We have to make sure Canadians are acutely aware of this and they should not approach the American border in a manner that invites suspicion,” he said.

Goodale said public education and information efforts will be stepped up regarding border travel, and said that signage on both sides will be important.