Australia’s highest court ruled Wednesday that the country’s detention of asylum seekers at sea last June was lawful — a decision that hands a major legal victory to backers of Canberra’s hardline immigration policy.

Australia had initially intended to send the group of Sri Lankan Tamils back to India, from where they had set sail. They were held on an Australian customs ship for weeks, and after refusing to cooperate with Indian consular officials were transferred to the South Pacific island of Nauru, one of the places where Australia has detention centers to hold asylum seekers until their cases are resolved.

At the time of that transfer in August, Hugh de Kretser, executive director of the Melbourne-based Human Rights Law Center, told the AFP news agency that the asylum seekers had been “locked in windowless rooms for at least 21 hours a day,” and that their "secret overnight transfer [was] a deliberate move to prevent legal scrutiny."

The ruling also means that the 157 asylum seekers — including 50 children — are not entitled to compensation for their treatment.

Brad Adams, executive director of Human Rights Watch's Asia division, told Al Jazeera that what Australia is doing with this court ruling is "very novel but also inconsistent with the intention of international law."

"International law would not allow a country to deny asylum seekers to apply on the soil of a third country and be held essentially in detention, in a legal limbo," Adams said.

"They're creating a Fortress Australia ­— they're putting walls around their country to try and stop anyone from reaching their shores," Adams added. "It's the politics of hysteria."

Potential consequences

Adams said the High Court’s decision Wednesday could have an effect on how some European countries, such as Italy and Greece, deal with the large waves of refugees from the Middle East and Africa.

"Europe is trying to come up with a system that doesn't violate international law, but ... this kind of decision, if it's upheld will certainly be very attractive to a lot of right-wing nationalists around the world," Adams said.

According to immigration figures, the facility on Nauru and another in Papua New Guinea’s Manus Island are holding nearly 2,400 people, with the situation on Manus — where dozens of asylum seekers are reported to have sewn their mouths shut in protest — being of great concern to human rights groups.

 Australia's Immigration Minister Peter Dutton said that the court’s decision Wednesday vindicated government policies, and that only one boat had reached Australia since the policies were implemented a year and a half ago.

"We have stopped people drowning at sea, we have stopped the boats and this government is absolutely resolved the operation will continue," Dutton said.

Australia received 16,000 asylum applications in 2014, a number that represents less than 0.5 percent of the over all asylum seekers worldwide according to U.N. figures. Canberra came under fire by rights groups after it was revealed that it planned to return Syrian refugees held on Manus to the war-torn country.

Accepting or rejecting asylum seekers is an important political issue in a country where current conservative Prime Minister Tony Abbott campaigned on the promise to "turn back the boats."

After the High Court case began, the government revised its immigration laws to reduce its obligations to follow international law and restrict the oversight of Australian courts, making it more difficult to launch such legal challenges in the future.

Al Jazeera and wire services