Thousands of Australians have urged the federal government to show compassion by halting the deportation of a Tamil asylum seeking family.

But the government's decisions about this case should not only be framed in terms of charity or benevolence.

There are legal obligations being overlooked by the government and in public debate that expose a protection gap with respect to children's human rights.

The decision to deport the family may be in breach of the Convention on the Rights of the Child (CROC).

The CROC is the most widely accepted international treaty. It has been ratified by every member of the United Nations except for the United States.

Many Australians want the government to show compassion to the Tamil family but there are legal obligations too. ( Supplied: @HometoBilo )

Nadesalingam, Priya and their eldest daughter have sought and been refused refugee protection in Australia.

There is an injunction in place restraining the family's removal from Australia until their youngest daughter's protection claim is heard.

But in addition to Australia's obligations to those in need of international protection, under the CROC Australia is obligated to give primary consideration to the best interests of children in any action concerning them.

Has the government ignored legal obligations?

This means that in making decisions about the family, including whether or not they should remain in Australia, the Australian government must have regard to what is in the two daughters' best interests and must give these factors high priority.

It is clear that the federal government has failed to comply with this international legal obligation.

The Minister for Home Affairs Peter Dutton has justified the decision to deport the family on the grounds that their refugee protection claims have been considered and denied by the Federal Court and High Court.

However, these legal decisions only concern whether or not Australia has protection obligations to each member of the family — they do not encompass whether removal of the family from Australia is in the children's best interests.

What is in the children's best interest could be undertaken as part of the Minister's discretion to intervene but the Minister has categorically refused to intervene in the case.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 7 seconds 1 m 7 s The family recorded a video as they were flown from Melbourne to Darwin

In any event, relying on ministerial discretion is an inappropriate and ineffective way to ensure Australia's compliance with its obligations under the CROC.

The Minister is not obligated to intervene and the guidelines on what the minister considers to be "unique and exceptional circumstances" warranting consideration do not explicitly mention children's human rights.

The Prime Minister has legitimised the decision on grounds of national security.

The UN Committee on the Rights of the Child states that other considerations can override the best interests of the child but only in exceptional circumstances.

Further, such a decision must be accompanied by credible reasoning explaining why the best interests of the child do not outweigh other considerations.

Is Australia out of step?

Australia is out of step with other countries in its disregard for the best interests of children in deportation decisions.

The Supreme Court of Canada, in a 1999 decision, ruled that the CROC requires that the best interests of the child must be considered and given great weight in the exercise of ministerial discretion in cases where international protection claims have failed.

And, in a 2011 case, the Supreme Court of the United Kingdom stated that the best interests of the child should be the first consideration in deportation decisions and no other factor is more significant.

Similarly, in France, judicial review proceedings consider the best interests of the child in cases where asylum seekers and migrants resist deportation.

Nadesakingam and Priya's children were both born in Australia, have started to build connections with their local community and have never been to Sri Lanka.

These factors alone indicate that it is most probably in their best interests to remain in Australia.

To ensure compliance with the CROC, Australia must establish a process whereby their best interests can be identified and given significant weight in any decision concerning them.

Kate Ogg is a senior lecturer in the School of Law at the Australian National University.