HALIFAX -- Intelligence and justice officials around the world will be watching Thursday as a navy officer convicted of selling military secrets to Russia becomes the first person to be sentenced under Canada's Security of Information Act.

Sub-Lt. Jeffrey Paul Delisle will appear in Nova Scotia provincial court for a two-day hearing after pleading guilty in October to breach of trust and passing information to a foreign entity that could harm Canada's interests.

The landmark case has captivated legal experts, international allies and intelligence agencies eager to see how the Canadian judicial system handles the treason of one of its own.

The challenge for lawyers and Judge Patrick Curran is how to come up with an appropriate sentence without having case law to consult under the untested act.

"It's going to be a very difficult exercise because there just isn't really a range that's been set out under this legislation," Mike Taylor, Delisle's lawyer, said in an interview Wednesday.

"Although there will be comparisons to the (Official) Secrets Act ... things are different and things have changed and the facts are different in those cases.

"We're comparing cases that don't necessarily lie on all fours. They're just not the same thing."

Taylor said he has been searching case law in the United States, the United Kingdom and Canada but found little that matches the unique circumstances of the agent who walked into the Russian Embassy in Ottawa in 2007 to offer his services after his personal life began to unravel.

Legal scholars say Curran will have a tricky time settling on a sentence since he will be faced with general sentencing principles that don't fit well with this type of offence, decades-old espionage cases tried under another act and what are expected to be widely divergent recommendations from the Crown and defence.

It's expected the Crown will ask for a hefty sentence in the interests of deterrence and show its allies it's taking the matter seriously.

Robert Currie, a professor of international criminal law at Dalhousie University, said the lawyers can apply standard sentencing guidelines, such as denunciation, deterrence, rehabilitation and reparations to the community, but that the gravity of the case makes it stand apart.

"The judge is going to have to reason from general principles of sentencing in a fairly new and specific context without really a lot of guidance," he said in Halifax.

"So I think we can be fairly confident that this will go to the higher levels, if not the highest levels of court. Whatever the result, it'll be appealed."

Taylor said he will argue that the damage Delisle is alleged to have done to Canada's relations with its allies and revelations about how its domestic spy service gathers intelligence has been overstated.

He will call a witness who is expected to challenge the damage assessments done by the Canada Security Intelligence Service, National Defence and Delisle's superior at Trinity -- the military all-source intelligence "fusion" centre on the East Coast.

In an injury assessment presented at Delisle's bail hearing, a CSIS official bluntly said that, "Delisle's unauthorized disclosures to the Russians since 2007 has caused severe and irreparable damage to Canadian interests."

The divorced father of four had top secret clearance, giving him access to secure information from the Privy Council Office, CSIS, the RCMP and some databases of Canada's allies.

On Jan. 11, 2012, Delisle thought he was transferring two CSIS intelligence reports to the Russians labelled "Canadian Eyes Only" when they were, in fact, being intercepted by the RCMP, according to the injury assessment. He was arrested at his home days later.

Taylor said he will also raise the issue of security at Trinity and how easy it was for the threat assessment analyst to use a crude system of floppy discs, USB sticks and an email program to smuggle secretive material out and transfer it to the Russian military intelligence unit from his home.

"I have to comment on the security issue to counter some of the weight that they're trying to dump on him," he said.

It's not clear whether Delisle will take the stand, but Taylor said the court will hear about his worsening financial and personal troubles that allegedly motivated him to betray his country.

In a statement to police after his arrest, Delisle broke down and insisted that his treachery began after he discovered his wife was cheating on him.

"I walked right in that Embassy and I said: 'Here I am.' It wasn't for money. It was never for money," he told an officer. "I thought of suicide so many times, so many times. I just couldn't ... So I committed professional suicide."

Crown attorney Lyne Decarie didn't want to comment on the case, saying only that she would call three witnesses. She has said one charge of breach of trust under the Criminal Code carries a maximum sentence of five years. The other two charges under the security act carry life sentences, though Decarie said she won't seek that.