Possessing marijuana is still a crime.

That's the message the Trudeau government is sending to Canadians four months ahead of the legalization of recreational cannabis.

Critics say that could have extreme consequences for people carrying a conviction even after pot laws change.

Come October 17th adults will be allowed to legally possess up to 30 grams of legal cannabis.

The law will create a new offence for possessing more than that amount.

The uncertainty over what will happen with previous convictions under the existing law has left a cloud hanging over the heads of some marijuana users.

Colin Kroeker supports legalization but he said once the law changes old convictions should be purged.

"Once it's legalized it only makes sense to have all those pardoned,” said Kroeker.

It’s still not clear whether that will happen.

Public Safety Minister Ralph Goodale told CTV Question Period the federal government will deal with the issue of pardons after legalization.

"When that law changes – which will happen on the 17th of October – then the government will turn its attention to those issues that arise once the law has changed," said Goodale.

Winnipeg defence lawyer Matt Gould said that means prosecutions for possession could continue even after recreational cannabis becomes legal.

"It's changing but it has not changed yet,” said Gould.  “The risks are high.  For simple possession there's not a lot of people going to jail for that but there are people getting criminal records."

Gould said right now people have to wait five years from the date of a conviction to apply for a pardon for marijuana possession.

He said if the government doesn't change that, a conviction for what Gould calls a minor offence could carry crippling consequences.

"The impact in terms of travel, going to the United States,” said Gould.  “The impact of employment opportunities."

“You might have someone who gets arrested for simple possession of marijuana before October 17th and that person, two years from now, might not be able to go, for example, to a wedding in the states. That person might have to give up a job opportunity.”

According to Statistics Canada cannabis-related offences declined for the fifth straight year in 2016.

Of 55,000 offences, 81 per cent were for possession

More than 17, 000 people were charged with possession offences in 2016, 3600 less than in 2015.

Chris Scott thinks there may be a case to keep cannabis convictions on the books because the marijuana sold came from the black market.

"I don't think they should be punished but I understand the rule of law doesn't really have that wiggle room," said Scott

Colin Kroeker doesn't see it that way.

He thinks previous convictions should be extinguished.

"Definitely small ones,” said Kroeker.  “Get those wiped right off."

If Canada pardons cannabis possession some experts have said other countries may not do the same, meaning Canadians carrying a conviction could continue to face barriers crossing borders.