The Biloela family would be automatically barred from returning to Australia if deported - and even if Immigration Minister David Coleman chooses to intervene, the family could be left with a seven-figure debt to the Commonwealth, a former senior Immigration official says.
The comments stand in contrast to Prime Minister Scott Morrison's claim the family could apply to come to Australia "as everyone else" could if their last ditch effort to stay in Australia fails.
Sri Lankan couple Priya and Nadesalingam and their Australian-born daughters Kopika, 4, and Tharunicaa, 2, are currently on Christmas Island, pending the outcome of a Federal Court case on Wednesday.
The family had been living in the central Queensland town of Biloela until Priya's bridging visa expired last March.
Mr Morrison ruled out in intervening in the case, saying it would "send exactly the wrong message" to people smugglers.
"They can return to Sri Lanka and they can make an application to come to Australia under the same processes as everyone else, anywhere else in the world. And I would hope they do. I would hope they do. But they didn't come to the country in the appropriate way. They have not been found to have an asylum claim," Mr Morrison said.
However Abdul Rizvi, who was the deputy secretary of the Department of Immigration and Citizenship from 2005 to 2007, said this statement was "misleading".
"If they're deported from Australia they're automatically subject to a bar under section 48 of the Act from the country," Mr Rizvi said.
"The minister can lift the bar, assuming the minister was inclined to do but even if the minister did, they'd still be left with a large debt to the Commonwealth, adding up all of the costs of their detention to date."
Mr Rizvi estimated the debt could well exceed $1 million.
"Just think about the cost of a charter flight to Christmas Island, that would have cost $60,000-70,000 alone," Mr Rizvi said.
Such debts had been used "many many times before" to keep people out of Australia.
"They're not always that large, sometimes they're in the hundreds of thousands of dollars," Mr Rizvi said.
"The person is not allowed to come back into the country until they pay, it's just a means of keeping them out."
The government could waive the debt, but Mr Rizvi suspected it would not do so.
"Once the government's got rid of the family, they won't want to see them back," Mr Rizvi said.
If Mr Morrison was genuine about hoping the family applies to come back to Australia, Mr Rizvi said the government could approve their return on a visitor visa.
The fact is we have a migration system which is straining, at straining point, because the government having created the Department of Home Affairs has lost a focus on immigration and processing.Labor's spokeswoman for Home Affairs Kristina Keneally
From there, the father could apply for a work visa, if he found an employer to sponsor them.
Then they could get on a pathway to permanent residency, Mr Rizvi said.
"This would mean they've exercised their discretion to help them stay permanently without breaking down that message about boat arrivals," Mr Rizvi said.
Mr Rizvi also said the immigration visa processing system was struggling under the weight of applications.
"What we've got is a system in paralysis," Mr Rizvi said.
"Processing times have blown out for so many visa types what people are doing is coming to Australia on a visitor visa, then applying for the type they want while on shore. We've seen a big increase in the bridging visa backlog as a result."
Labor's spokeswoman for Home Affairs Kristina Keneally blamed the strain on the absorption of immigration into the mega Home Affairs portfolio.
"Spouse visas, which are relatively straightforward are now taking over two years. Citizenship applications, which I myself, by the way, have completed - it took only a few weeks because citizenship should be at the end of a process where you've gone to permanent residency - that's now taking over two years," Senator Keneally told AM.
"We have asylum claims that are taking two to four years to assess and those are the people who come by airplane with papers. The fact is we have a migration system which is straining, at straining point, because the government having created the Department of Home Affairs has lost a focus on immigration and processing.
"That undermines public confidence, it undermines the capacity of business to bring in skilled workers and it certainly is putting great pressure on families who are trying to get parents or spouses to be able to join them in Australia. We used to do these things quite quickly and efficiently and we are simply not any longer."
But Home Affairs Minister Peter Dutton turned the blame back on those applying for visas.
"If people seek to drag matters out for years and years and years, then that is an issue for them, but there are 1500 people from Sri Lanka who came here originally by boat who have gone back, exactly the same family units," Mr Dutton said on Tuesday.
"Young boys and girls, mums and dads that wanted a better future in Australia, but, as we have said, we are not going to allow people to settle who come by boat and we will look at individual cases, as we have done here, but, clearly, every decision maker right to the High Court has found these people are not refugees."
Mr Dutton also said the government intervened "compassionately" in hundreds of cases per year.
"They never make it to the media. But we are able to provide an outcome for a child with a terminal illness, somebody who has had a stroke here visiting children or grandchildren, we are able to provide compassionate support in those cases," Mr Dutton said.
The Home Affairs department declined to comment.