Lawyers for a Canadian accused in a massive hack of Yahoo emails say a judge who denied their client bail overstated his alleged role in the scheme.

Karim Baratov's legal team was in court Monday appealing an April ruling by Ontario Superior Court Justice Alan Whitten, who decided the 22-year-old was too much of a flight risk to be released on bail.

Baratov was arrested in March under the Extradition Act after U.S. authorities indicted him and three others -- two of them allegedly officers of Russia's Federal Security Service -- for computer hacking, economic espionage and other crimes.

Baratov's lawyers argued Monday that Whitten had made several errors, including amplifying the Hamilton man's alleged connection to the Yahoo hack and the Russian intelligence agent who allegedly hired him.

"(Our argument is) painting him as a small fish, and not affiliated to the Yahoo hack," Baratov's lawyer Amedeo DiCarlo said outside court.

Ravin Pillay, another one of Baratov's lawyers, said in court that there's no evidence to suggest his client was involved in the large-scale breach of Yahoo security systems.

Emails between Baratov and his alleged contact in the Russian intelligence service show he was only allegedly hired to hack into 80 accounts, and only allegedly succeeded in accessing seven, Pillay said.

Hacking into several individual accounts is "fundamentally different" from breaching Yahoo's security system and gaining access to data from nearly half a billion accounts, Pillay argued.

"There's no evidence that Mr. Baratov knew who (the person who hired him, Dmitry) Dokuchaev was or that he was FSB," Pillay said.

He also noted that Dokuchaev only allegedly transferred $104 into Baratov's PayPal account.

"If the applicant knew he was dealing with a government official from another country, $104 is not a lot of money for his trouble," Pillay said.

But Crown Attorney Heather Graham said that money is only what was allegedly transferred to Baratov's PayPal accounts, suggesting further funds could have been sent to other accounts American investigators have not been able to access.

In denying Baratov bail, Whitten had rejected a defence's proposal that the man be released into the care of his parents, who offered close to $1 million in cash and assets as collateral.

Whitten said he believed Baratov would be motivated to flee, given that he could face up to 20 years in prison if convicted in the U.S.

But Pillay said Baratov doesn't pose a flight risk because there's nowhere for him to flee to.

American authorities have alleged in court documents that Baratov, who was born in Kazakhstan, posed an "extremely high flight risk" in part due to his alleged ties to Russian intelligence agents and his financial resources.

A decision on Baratov's bail appeal is expected later this week.