By Jane Wardell
SYDNEY (Reuters) - Australia's highest court gave the United Nations permission on Tuesday to give evidence in a groundbreaking legal challenge to the country's power to intercept asylum seekers' boats outside its territorial waters.
The intervention of the UN High Commissioner for Refugees (UNHCR) in the case of a group of Sri Lankan asylum seekers reflected the level of international concern over Australia's treatment of asylum seekers on the high seas, lawyers said.
The High Court in Canberra will decide on the legality of the treatment of the 157 Tamil asylum seekers who were held at sea for almost a month before being transferred to Australia and then again to a detention center on the South Pacific island of Nauru.
It is the first time the government's secretive "Operation Sovereign Borders" has been tested in court. The judge who referred to the case to an expedited full hearing in the High Court, Justice Kenneth Hayne, said it appeared to be unique.
"The implications for this case could be quite significant depending on how brave the High Court is and how far it decides to extend the power of the law," said Joyce Chia of the Kaldor Centre for International Refugee Law at the University of New South Wales.
The government is already moving to block any repeat case. It introduced a bill into parliament last month to change the Maritime Powers Act that would reduce its obligations to follow international law and restrict the oversight of Australian courts.
"This is a deeply, deeply concerning law and a deeply concerning power that the government is trying to give itself," said Daniel Webb, a director at the Human Rights Law Centre, which is advising on the current case.
Australia received 16,000 asylum seeker applications last year, just under 0.5 percent of the 3.6 million lodged worldwide, UN figures show. But it is a polarizing political issue. Conservative Prime Minister Tony Abbott campaigned heavily on the issue before winning elections last year.
The boat at the center of the case was intercepted in late June in the contiguous zone just outside Australia's territorial waters. Australia held the group in international waters for 28 days while it negotiated with India about returning the group.
The government did not publicly acknowledge the group's existence until after legal action was launched to prevent them from being returned to India or sent to Sri Lanka.
Australian Immigration Minister Scott Morrison has said he is confident the group were economic migrants and therefore not entitled to asylum.
The UNHCR, which in July expressed "profound concern" over the case, will not be a direct party to the case but was granted leave to file written submissions about Australia's obligations under UN conventions.
The new UN High Commissioner for Human Rights, Zeid Ra'ad Al-Hussein, last month used his maiden address to accuse Australia of a "chain of human rights violations" in its treatment of asylum seekers.
The last time the UNHCR sought such an intervention in Australia was in 2006 when it joined a case about temporary protection visas for refugees.
The High Court does not have the power to order the detainees be returned to Australia from Nauru, but can compel the government to pay the group compensation if it finds in their favor.
Chia said the case was being closely watched. If the judges find in favor of the asylum seekers on international law issues, the case could be cited elsewhere in the world to support claims by asylum seekers.
"I think the court may well decided that this case steps over the line ... because it is an extraordinary example," she said.
The Australian Human Rights Commission, which earlier this year held an inquiry into the wellbeing of children in Australia's immigration detention centers, was also given permission to file written submissions to the court.
Both the UNHCR and the HRC were denied a bid to provide oral submissions.