The Australian Federal Government's welcomed a High Court decision, that's found detaining 157 Tamil asylum seekers on an Australian Customs boat was legal.

The case was mounted by a Tamil Christian man, who was aboard the vessel which departed India, and was intercepted off Christmas Island last June.

Immigration Minister Peter Dutton says they'll now further analyse the judgment.

"There's 157 page judgement that the Government will now consider in detail, but it has vindicated the Government's position and we welcome the result."