The Howard government made contradictory public statements about the fairness of the military commission trial in the US of former Guantanamo Bay detainee David Hicks, according to new documents.

The heavily redacted documents, obtained under freedom of information, include emails, advice and cables between Australian government officials and US officials in relation to the US military commission process and Mr Hicks' case.

Seeking truth: David Hicks. Credit:Kate Geraghty

Human rights advocate and lecturer Aloysia Brooks - who is married to Mr Hicks - obtained the documents, which show the Attorney-General's Department was aware the military commission could allow evidence obtained by the use of torture due to its broader definition of what torture was.

The January 2007 departmental background briefing document says there are some protections against the use of statements obtained by torture. But it warned: ''However, the US definition of torture opens the possibility that evidence obtained by the infliction of severe mental suffering which does not result in 'prolonged mental harm' or which is inflicted by methods other than those set out in the manual will not be considered to be 'torture' and so will be admissible before a military commission. A statement alleged to be the product of coercion may also be admitted into evidence in certain circumstances.''