17:00 AEST UPDATE: Asylum seekers given reprieve of at least 72 hours before they face being handed to the Sri Lankan government.
The government has told the High Court it will not return asylum seekers without 72 hours notice. Hearing is adjourned until Friday.
The asylum seekers are now in legal limbo.
"Govt lawyers say therefore the asylum seekers have no right to asylum in Oz They're now on the "high seas" on customs vessel #hcchallenge"
Theoretically they could be at sea for up to 21 days.
Adjourned. There'll be a Directions Hearing within 21 days. The asylum seekers could be on the high seas for that time #hcchallenge
Overnight, Australian refugee lawyers launched a spectacular last ditch appeal for 153 asylum seekers "whose precise location is unknown", set to be sent back to Sri Lanka.
The High Court will decide this afternoon whether returning the Sri Lankan and Tamil asylum seekers violates Australia's legal obligations.
The case of the "disappeared" has fired up progressives in Australia... including lobby group GetUp! who filmed a former Sri Lankan asylum seeker pleading with Immigration Minister Scott Morrison not to send them back.
And others people have reacted with disappointment...
The owl and the pussycat, with apologies.
Mostly by pinning the blame on the Immigration Minister.
Scott Morrison hates the bit in Sound of Music where the Von Trapps flee to safety.
And now the world is watching Melbourne, where the High Court hearing starts at 2pm AEST
Australia's treatment of Sri Lankan asylum seekers on front page of UK Guardian tomorrow: