After 11 September, 2001, customs officials zealously applied a law prohibiting any foreign national with even a minor criminal record from entering the country, unless they obtained a waiver from the US government.
Quebec businessman Pierre Charade, who has crossed the US-Canadian border several times each year without facing any problems, was on a business trip to Florida with his colleagues when one youthful indiscretion stopped him in his tracks.
The TV producer said an immigration officer searched through his computer for criminal records against him and his travel colleagues.
"When he came out of his office, he said to me: 'Sir, you are a criminal. You were arrested in Toronto 36 years ago,'" Charade said.
"I thought it was a joke. I even looked around for a hidden camera and then he said to me: 'No, you are not welcome in the United States.'"
For breaking a school window 20 years ago with some friends, Charade had been sentenced to a $72.50 US fine.
The price he must pay today is much higher, on both professional and financial levels.
If Charade, in his 50s now, wants to cross the border, he has no choice but to obtain a waiver, which costs an average of $250.
Added to that are fees charged by Canadian groups to assist people in obtaining the US waivers. They can range between $400-$543.
The Canada-US border is the
world's largest undefended border
One of these groups, the Montreal-based National Pardon Centre receives about 100 calls daily from businessmen, truck drivers and other Canadians obligated to clear their names for entry.
"For two years now, we've heard from a lot of people, who never had problems crossing the border, saying they were surprised to be refused entry," said spokesman Shereef Elshasei.
If US officials seem zealous the first instance a person with a criminal record tries to enter the United States, every other attempt risks resulting in the seizure of goods or even the locking up of the individual, he said.
"Everything is up to the discretion of the (US) agent," he said, noting that drunk driving infractions pass but not drug possession charges.
"Their methods are sometimes a bit cowboyish," Elshasei said.
Another case in point, according to the centre's records, was a resident of Montreal who was stopped in Miami on his way to the Caribbean.
"When he boarded, he was handcuffed and spent the night in jail before being sent directly back to Canada on a flight," said Elshasei.
For others, the problem is not so dramatic, but simply humiliating.
One businessman had to suffer through an agent asking, "Which one of you two is the criminal?," he said.
With Ottawa and Washington having strengthened bilateral cooperation to fight "terrorism", US customs officials have access to computer criminal records from Canada's federal police, the Royal Canadian Mounted Police, making it easier to spot a minor infraction.
Between five and 10 percent of the 31 million Canadians have a criminal record.
Since US authorities accord only one-year to five-year waivers, Canadian sins could be a major bonanza for US coffers well into the future.