Most travellers are meant to be processed in under a minute by front-line border agents, who don't have access to the Canadian Police Information Centre (CPIC) database.
CPIC contains criminal records, outstanding arrest warrants and other security information compiled by police.
It may seem ironic, but American border agents use CPIC at the primary inspection line to help screen travellers, while visitors to Canada aren't all screened with this Canadian tool.
The head of the union that represents border officials said Canadians should be not only surprised but also "concerned" about the way security is handled at the border.
"CPIC is accessible, but not at the primary, which is actually the first contact you're having with one of our officers," said Jean-Pierre Fortin, head of the Customs and Immigration Union.
That means a person coming into Canada must first be deemed suspicious by a front-line agent in order to be sent to a secondary officer where a CPIC check can be done.
The reason, Fortin said, is time. CPIC isn't made available to front-line officers, he said, mainly because the government doesn't want to "slow down the traffic" at the border.
"They want to make sure that people are being processed within a time frame of seconds every time they're coming into this country," he said.
A spokesperson for the Canada Border Services Agency (CBSA) said officers at secondary inspection lines have greater access to "various databases," but did not address questions about access to CPIC at the primary inspection line.
CBSA said front-line officers scan travellers against CBSA's internal lookout system, which contains information about some people being sought by immigration authorities.
Agents on the front lines also have access to a database of lost, stolen or fraudulent documents.
If you aren't in the CBSA's lookout system, said Fortin, "you know, you're coming in and we don't even know if you're a criminal or not."
Wanted man allowed into Canada
A CBC News investigation earlier this year revealed that a Nigerian priest charged with sexual assault in Canada was allowed through the border, despite an outstanding warrant for his arrest.
Father Anthony Onyenagada is accused of assaulting a female parishioner at a Southern Ontario Catholic church he visited in 2004.
By the time local police laid charges against him, he had left Canada. Police assured the woman the priest would be arrested if he ever tried to re-enter the country.
Then, nearly 10 years later, the woman found evidence that he had recently been back.
CBC News has agreed not to identify the woman.
In response to the new revelations about front-line border intelligence, she said, "I don't understand how somebody who has outstanding warrants for their arrest isn't enough to trigger the border system to look at them."
At the time of his entry, the priest would have needed a visa issued in advance.
CBSA said it won't comment on specific cases and that traveller admissibility is determined "based on the information made available at the time of entry."
The agency would not say what information was missing when Onyenagada was allowed through the border, nor would it provide CBC with statistics on how many other inadmissible or wanted individuals have gained entry to Canada.
More training needed: former border guard
Former border agent Arne Kislenko, who now teaches at Ryerson University and the University of Toronto, said he isn't surprised the priest got in.
"Everything is reliant upon that front-line officer's assessment, which is made in a very short period of time," Kislenko said.
Kislenko said it boggles his mind that front-line officers don't have access to CPIC.
But he said, "As a private citizen and as an academic, I have to say we need to be careful. Putting tools into play is a great idea if they're managed properly — if you have people that are trained properly on them."
Some of those front-line officers, he said, don't have adequate experience or training.
He said CBSA has been moving away from having inexperienced officers on the front lines, but even recently the agency has had summer students working at the border.
"I love students," he said. "But you know, putting inexperienced officers or marginally experienced officers at the front line is to me a real head-scratcher."
For Fortin, the lack of tools for front-line officers represents a loophole.
"They're going to have to provide us with the entire tools in order to detect criminals coming [into] this country," said Fortin.
He said another concern is that the government has been reducing the shift hours for border officers in some parts of Canada.
The woman whose alleged attacker slipped back into Canada said she's confused that "they're trying to spend all this money on terrorism and stuff, and they can't catch a simple priest that was wanted."
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