WITH his pledge to “stop the boats”, Tony Abbott, then the leader of Australia’s opposition, made a crusade against asylum-seekers a key part of last year’s victorious election campaign. Last month the prime minister claimed victory: Mr Abbott boasted that his conservative Liberal-National government had notched up six months without one “people-smuggling venture” landing on Australian shores. It has done so mainly by using the navy to push boats back to Indonesia, from where most asylum-seekers set out.

Days after his declaration, Australia seized 157 Sri Lankan Tamil asylum-seekers from a boat near Christmas Island, an Australian territory in the Indian Ocean. The government has since held them on a customs vessel at sea, though it will not say where. The boat people’s fate has now moved to Australia’s High Court, where refugee advocates say the government is acting illegally. The case could affect the policy of turning back the boats.

When reports of the boat’s seizure first surfaced, Scott Morrison, the immigration minister, refused even to acknowledge the interception. The government calls “Operation Sovereign Borders” against boats a “military-led” affair, and has shrouded it in secrecy. It then emerged that Australia had intercepted another vessel, carrying 41 Sri Lankan asylum-seekers, both Tamil and Sinhalese. It handed these people over to a Sri Lankan naval vessel off the coast of Sri Lanka in early July.

That prompted lawyers, backed by the Human Rights Law Centre in Melbourne, to go to the High Court. On July 7th a judge issued a temporary injunction stopping the larger group of boat people from being delivered to Sri Lanka, too. In preliminary hearings since, some details have come out. The 157 Sri Lankans had left for Christmas Island from southern India. Since their interception, they have been allowed out of their cabins on the Australian vessel for meals and three hours of daylight a day. Family members, among them three dozen children, have been split up.

According to court documents, the cabinet’s national-security committee, which Mr Abbott chairs, ruled two days after the Sri Lankans’ interception on June 29th that they be taken to “a place other than Australia”. A destination has not been spelled out. But the government has undertaken to the court that it will not send them to Sri Lanka without notice. Mr Morrison’s visit to Delhi on July 22nd sparked speculation that Australia hoped to send the asylum-seekers to India instead.

The government says the Sri Lankans were intercepted in a “contiguous zone” just outside Australia’s territorial waters around Christmas Island. It argues this makes them ineligible to claim asylum in Australia, and that the country’s Maritime Powers Act allows it to transfer them elsewhere. The boat people’s lawyers contend that Australia’s obligations under international and human-rights laws apply as much as Australian law on the high seas. They say this means Australia should give the boat people a fair hearing and not send them to a country such as Sri Lanka, where some may fear for their safety.

The government has acknowledged that the 41 people from the earlier boat were given a rather compressed form of screening before being handed over to Sri Lanka. Australia has used a blunt process of shortened questioning, often without access to lawyers, since 2012—mainly with boat people from Sri Lanka. Many have been returned there as a result. The UN refugee agency has condemned the practice. On July 7th some 53 legal scholars from 17 Australian universities declared jointly that Australia’s “reported conduct under Operation Sovereign Borders clearly violates international law”.

Some critics worry about other cosy aspects of Australia’s relations with Sri Lanka. Two months after its election last year, the Abbott government gave Sri Lanka two patrol boats to help it stop asylum-seekers from leaving the country. Gillian Triggs, head of Australia’s human-rights commission, speaks of a “dangerous environment” after Sri Lanka’s bitter civil war ended in 2009 with the government’s crushing victory. But Mr Abbott sounds sanguine. Sri Lanka, he says, “is not everyone’s idea of the ideal society, but it is at peace”.

The High Court is due to hear the Tamils’ challenge on August 5th. Meanwhile, about 2,300 asylum-seekers intercepted at sea in recent years are waiting to have their claims processed in two detention camps, one on the tiny island-state of Nauru and the other on Manus Island, in Papua New Guinea. David Manne, a lawyer for refugees, says that if the court ruling went against the government, it would force a profound change in how Australia treats them and other asylum-seekers at sea.