Perhaps that is so, if a decision based on interpretation of our constitution and laws passed by Parliament is the sole criteria for determining legality, but even so, I favour the dissenting voice of Justice Michelle Gordon, who argued that “The relevant section of the Migration Act is invalid”.

However, and very sadly, the majority rules, but that does not make their decision morally or ethically right. Their decision cannot be justified for either adults or children, though some media commentators such as the Sydney Moring Herald editorial (February 4) argue, wrongly to my mind, that “The Herald accepts it can be justified for adults, but there is no moral justification for punishing children for the "sins" of their parents”. Well yes, but of what sins are these particular parents guilty? None, of course.

This appalling situation is best summed up by esteemed commentator Waleed Aly, who asked, late last week, “How long can we keep lying to ourselves? The history of asylum seeker policy in Australia will be remembered as a story of how successive governments legislated their lies to justify a world of make-believe borders and imaginary compliance” (SMH, February 5).

The test case was run by the Human Rights Law Centre on behalf of a Bangladeshi national who was sent by the Australian government as an "unauthorised maritime arrival" to Nauru, then brought to Australia in August 2014 for medical treatment along with her baby daughter.

The baby is one of 37 facing immediate deportation from the Wickham Point detention facility near Darwin to Nauru as a result of the decision. The Immigration Minister, Peter Dutton, has made clear his determination to enforce a "robust" approach.

True, the federal government in response to widespread outrage has belatedly worked to reduce the number of children held in detention, from nearly 1000 in mid-2014 to 174 at the end of last November. Of those still in detention 104 were held in closed immigration detention facilities in Australia and 70 in the Regional Processing Centre in Nauru. A further 331 children were in community detention in Australia.

On Nauru they face rat infestations, extreme heat, poor access to water, insufficient health screening, the threat of sexual assaults and prolonged uncertainty about the future. Not surprisingly the coincidentally new Human Rights Commission inquiry report found that "children on Nauru are suffering from extreme levels of physical, emotional, psychological and developmental distress".

As Professor George Williams notes, there is now no need for asylum seekers to be treated fairly with prompt assessment of claims, and the law allows Australia to wash its hands of such matters by sending them to Nauru. In response to his first question since yesterday’s High Court decision Prime Minister Malcolm Turnbull refused to commit to not sending these children currently living in Australia to Nauru.

Greens Immigration spokesperson Senator Sarah Hanson-Young said: “When it comes to people seeking asylum, we need to create a fair and efficient system that will bring them here safely so that they can be integrated into the community.”

Indeed, all asylum seekers, including of course, parents with children, should be subject to community detention, not imprisonment in detention centres.