Lisa Kirkman's son spent almost two years in foster care in Oregon before returning to Calgary in June. (CBC)

The government of Oregon has "colossal nerve" to sue a Calgary woman whose son was kept in foster care in the U.S. state for nearly two years, her lawyer says.

"I want to say to the State of Oregon, 'Shame on you. We know you've got budget problems, everybody knows that, but do you really think you're going to fix them by going after a single mother of modest means?'" Daniel Mol said at a news conference in Calgary on Monday.

Oregon is seeking to recover from Lisa Kirkman the costs of her boy's foster care in the U.S. The matter was set to be heard in Alberta provincial court in Calgary on Tuesday.

Mol said that his client is going to "hit back" at the state and that he has filed an application on her behalf to have Oregon's action dismissed.

"It's also our firm intention to bring legal action against the government of the state of Oregon and against the Canadian government for compensation for this family, but most importantly, to make sure that this doesn't happen to any other Canadian family," Mol said.

Kirkman ordered to undergo assessment, parenting classes

In 2008, Kirkman's son, who was 10 at the time, went to Oregon to visit his stepfather. The boy cannot be identified.

That summer, local police became concerned about the boy's behaviour. He suffers from several mental health problems, including obsessive compulsive disorder and a severe form of attention deficit disorder, according to his mother.

When police stopped him for riding a bike without a helmet, they alerted the state's Department of Human Services, who contacted their counterparts in British Columbia and Quebec, where the family used to live.

Kirkman said that based on her son's lengthy files in those jurisdictions — including periods of part-time therapeutic foster care in B.C. — U.S. officials took him into state care.

He was placed with several foster families during his time in Oregon.

The state didn't recognize the boy's stepfather as his legal guardian, and the judge overseeing the case ordered Kirkman to complete psychiatric assessments, home studies and parenting classes — which she did.

The boy arrived back in Alberta in June.

'Judicial child abduction'

Kirkman has previously said the judge responsible for the case in Oregon was biased against her because of her criminal conviction in Canada for growing marijuana in 2003, her current status as a medical marijuana user and her background as a pot activist.

In March, Regina lawyer Tony Merchant, who was representing Kirkman in Canada at the time, said the case "almost feels like judicial child abduction."

"They don't have any confidence in Canada," Merchant said of the U.S. authorities. "It's almost as though they're saying you can't go back to Calgary because it's cold up there. Or you can't go back to Calgary because we don't really understand the strengths and the protections that exist in the Canadian system."