A court ruling on Thursday in support of two Sri Lankan asylum seekers could force a change in Australia’s refugee policy, which has different rules for those who apply offshore and those who apply on the mainland.

Australia’s High Court unanimously declared it was an error of law to deny asylum seekers on the Australian mainland the right to apply for refugee status.

The two Sri Lankan men, who were not identified by name in court, have been detained since October 2009 on Christmas Island after illegally entering Australian waters. They claimed to be refugees fleeing persecution in Sri Lanka due to their support for Tamil Tiger rebels.

But their applications for refugee visas were denied, and they faced deportation before they appealed to the High Court.

Under current law, rejected refugee applicants on the Australian mainland can appeal to the immigration minister, who has the power to grant visas.

But asylum seekers from outside Australia’s migration zone, such as those housed in detention centres on Christmas Island, do not have the same access to courts and appeals.

It was not known why their refugee applications were rejected, and because the Sri Lankan plaintiffs were detained at Christmas Island they could not appeal to the immigration minister.

Immigration Minister Chris Bowen said the judgment had “significant ramifications” but denied that it questioned the validity of offshore processing.

“The preliminary advice to me is that there is not a significant implication for regional processing, but of course I will be seeking further advice,” Mr. Bowen told reporters in Sydney.

Attorney—General Robert McClelland also said offshore immigration detention was not in question but that the ruling indicated some reviews were necessary.

“Additional review is appropriate in respect to legal matters relating to the decision—making process, including potentially those relating to the issue of procedural fairness,” Mr. McClelland told Sky News.

Opposition Deputy Leader Julie Bishop, said the High Court judgment represented a failure of the ruling party to implement effective border protection and immigration laws.

“The processing system is now in chaos as a result of this High Court ruling and detention centres are being opened up across Australia to cope with people coming,” Ms. Bishop told Australian Broadcasting Corp. radio.

Constitutional law expert George Williams of the University of New South Wales said the court’s decision would affect how individual asylum cases are handled but would probably not bring an end to offshore processing.

“It’s something that will have a big impact on how these people are dealt with in the coming years, as they now do have access to the courts, do have a set of rights that were thought to be beyond them,” Mr. Williams said. “That will mean the government will have to look very carefully at how the processing is occurring at Christmas Island.”

Australia has long been a destination for people from poor, often war—ravaged countries hoping to start a new life. Most asylum seekers in recent years have come from Afghanistan, Iran and Iraq. They typically fly to Indonesia before continuing to Australia in cramped, barely seaworthy boats.

This year, more than 110 boats carrying asylum seekers have entered Australian waters. Their occupants have been detained at either Christmas Island or mainland detention centres while their refugee claims are assessed.

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