An Immigration Review Board adjudicator has dismissed allegations by the federal government that a Tamil migrant who arrived on a ship in Victoria last summer was part of a terrorist group.

Leeann King ruled the man can make a refugee claim in Canada and she systematically dismantled the federal government's evidence against him, calling the information trivial, unreliable and riddled with mistakes and speculation.

"In this case, what [the man] has told officers and what he testified to before me about what happened to him in Sri Lanka is the only credible and trustworthy evidence before me," she concluded in her ruling Thursday.

The claimant, who can't be identified, is one of almost 500 people who arrived aboard the MV Sun Sea last August on B.C.'s shore.

So far, the government has lost five of seven hearings where it alleged a migrant aboard the ship was a terrorist.

The federal government claims about four dozen of the group should be deported because they were either involved in the Tiger terror group or helped in the smuggling operation.

The Tigers were the losers in a decades-old civil war with the Sri Lankan government which ended in 2009.

During an earlier hearing, the man testified he was abducted by the Tigers who are also known as the Liberation Tigers of Tamil Eelam, or LTTE, but escaped shortly afterwards.

Months later, he was interrogated and tortured by the Sri Lankan army.

The government claimed the man's interviews with Canadian officials were full of inconsistencies and contradictions, which prove he was part of the terrorist group.

But King found few discrepancies.

"The inconsistencies the minister relies on are really very few and very trivial."

She noted the evidence was given through an interpreter, and the man was asked to recall information that happened years ago during a time of displacement and war.

In fact, in her years of experience reading transcripts she said the evidence presented by the man "demonstrates a very high degree of consistency."

King also criticized documents the government used to shore up its case against the man, saying they were riddled with errors, and in one case said the man's mother tongue was English.

"Clearly a significant mistake," she added.

In another document, the government relied on one line that said "forced, fully, specialization, ground groups alias." King said the document didn't make sense.

"The minister had constructed the theory that the man must have been a member of the LTTE."

The man testified that he did admit to the Sri Lankan army that he worked for the LTTE for over a year, but that was only to stop the torture and beatings while he was being detained.

Of the 492 migrants who were detained after their arrival, just 19 remain in detention.