High Court throws out challenge to Australia's immigration detention on Nauru

Scores of asylum-seeker families face being returned to Nauru after the High Court rejected a legal challenge to Australia's offshore immigration detention regime.

The full bench of the High Court handed down its ruling on Wednesday after considering the case of a pregnant Bangladeshi asylum seeker who was brought to Australia from Nauru for treatment of serious health complications.

She faced the prospect of being returned to the Pacific island with her one-year-old child.

However, the ruling also has implications for 267 people - including 91 children - who were also brought to Australia for medical treatment.

The federal government, with Labor's support, had retrospectively changed laws to shore up the Commonwealth's ability to pay for the offshore facilities.