A Brisbane grandmother who has lived in Australia for 50 years is set to be deported after Assistant Minister for Immigration Alex Hawke denied her permission to stay in the country.

Maryanne Caric has not left Australia since she arrived with her parents as a two-year-old from the then Republic of Yugoslavia, and does not speak Croatian.

On March 1, Ms Caric, a convicted drug offender detained in Sydney's Villawood detention centre, was handed deportation papers. She has no connections in Croatia, and as far as she knows, will receive no financial or health support.

It's a case that raises questions about where Australia's obligations lie, and what responsibility we have for our citizens and non-citizens.

Ms Caric has been caught up in legislative changes introduced in 2014 which, among other provisions, made it mandatory that any non-citizen who was sentenced to imprisonment of 12 months or more, would have their visas cancelled.

A statement to The Law Report from the Department of Immigration said: "The vast majority of this group has committed serious or violent crimes."

When a migrant is deemed to have failed the character test under Section 501 of the Migration Act, their visa is cancelled. Many of these so-called "501s" have been New Zealanders.

Visa cancellations can be revoked by ministerial intervention, but in most cases that doesn't happen. In Ms Caric's case, Mr Hawke has acknowledged her likely fate in Croatia.

In his decision, obtained by The Law Report, he said: "I accept that having been away from her country of origin for close to 50 years and having no personal support network there, together with her health and substance abuse issues, that it would be extremely difficult for her to make the necessary adjustments to life there."

'I thought I was living as an Australian'

Ms Caric, who is also known by her birth name, Mirjana, is a lifelong drug user and offender. She is not sure how many years she has spent in jail. "In the double figures," she said in an interview from Villawood detention centre.

Many of her convictions were for possession, but she has also been convicted of supply, and of trafficking — a definition which can apply to supplying more than three people.

None of the offences were violent. "I've never broken in to people's houses or anything like that," she said.

Ms Caric left home in Brisbane at 14, fleeing a violent alcoholic father. Her older sister Katrina had already left, after marrying at 16. Katrina would continue to look out for Maryanne over the tumultuous years that followed.

At some point Maryanne, who has a broad Australian accent, slipped through the citizenship net. Katrina became a citizen when she married, and she later organised her parents' citizenship papers.

But Maryanne wasn't around at the time. She told The Law Report she never thought about visas or citizenship.

"I thought I was living as an Australian," she said.

"I class myself as an Australian. I have never been anywhere else. I've never left the country. I've never wanted to."

In Mr Hawke's decision, he said: "I find that the Australian community would expect non-citizens to obey Australian laws while in Australia."

Ms Caric's lawyer, Jason Donnelly, who wrote her submission to revoke the visa cancellation, said the decision not to revoke is "unreasonable in the moral sense".

"I think if you are a non-citizen who has only lived here for a small portion of your life, then I would probably say there is very good reason for Australia exercising its sovereignty to deport that person to their country of national origin," he said.

"However, for all intents and purposes Maryanne, coming here as a two-year-old, is Australian. And I think Australia does need to exercise a fundamental sense of compassion."

Caric received official warnings

In the latter half of her life, Ms Caric was officially warned, twice, in 2007 and 2010, that further criminal activity could result in deportation. She said she thought about applying for citizenship then, but figured there was little chance with her criminal record.

Mr Donnelly, who is a barrister and migration agent and lectures at the University of Western Sydney, queries these "so-called warnings", which are often given to people while they are in prison.

"They're often without the benefit of a lawyer, even often without the benefit of Legal Aid," he said.

"They don't often understand the legal effect of what those warnings mean.

Maryanne Caric (front left) left home in Brisbane at 14, fleeing a violent alcoholic father. ( Supplied: Maryanne Caric )

"You can appreciate someone who has been an unfortunate long-term drug user might not necessarily understand the legal effect of what she is doing."

In his decision, Mr Hawke cited legal judgments where Ms Caric had been criticised for violations of parole conditions, uncooperative behaviour, and her repeated failure to cease offending, and to cease using drugs.

Ms Caric said she did try at times to get off drugs, but found it hard to get support. There is a chronic shortage of drug rehabilitation options in Australia.

"There's not that much help out there. You've got to have funds to go into these places. I had no funds," she said.

Drug use may not be over: Hawke

In 2015 Ms Caric was convicted of possessing 2.4g of pure heroin.

When her car was pulled over and the heroin found, police also found four mobile phones which indicated she was buying and selling illegal drugs.

Maryanne Caric in 2011, after taking part in a reality TV series called "Conviction Kitchen". ( Supplied: Maryanne Caric )

Mr Hawke said although she had stopped using drugs during her most recent incarceration and detention, he wasn't persuaded she would desist in the future.

"She may again resort to drug use and criminal activities," he said.

Ms Caric said she was not asking anyone to feel sorry for her over her criminal history.

"What I'm asking is: I have lost everything. I have done all my jail. I have never run from the authorities. I've gone to court," she said.

"I didn't set out to break any laws. This has been my life. And it's been quite a miserable one.

"All I'm asking is please let me die in Australia. I just don't understand. I'm not a terrorist, I'm not violent, I'm not a bikie.

"I have two grandchildren. That's all I have left and now they want to take that from me."

Caric 'learnt her crimes' in Australia

Ms Caric's partner of 21 years died a year ago, just after she was brought from Brisbane to Villawood.

His body is still in the morgue. She is his next of kin, and she said the Immigration Department has told her it's not possible for her to bury him.

She is worried about methadone, which she is dependent on, not being available to her in Croatia, and that she will be living on the street.

"Sending me over there is sending me over there to die. I'm not getting on that plane," she said.

Mr Donnelly, her lawyer, said that although Mr Hawke is obliged to consider community safety in Australia, that is not the only issue at play in the case.

"Effectively what Australia is doing with long term non-citizens like Maryanne is deporting Australia's problems," he said.

"Maryanne learned her drug problems in this country, learned her crimes in this country. In fact, she learned everything about her life in this country."

Ms Caric plans to appeal the Assistant Minister's decision.

Her weary sister Katrina is dealing with a cancer diagnosis and an elderly mother in a nursing home who does not know Maryanne is to be deported.

"She's an idiot," Katrina said of Maryanne. "But she belongs here."