ANY doubt that David Hicks was charged with war crimes for purely political reasons has gone, his father and his lawyer say.

The former chief prosecutor of the US military commissions at Guantanamo Bay said overnight he would not have pursued Hicks because the case against the Australian was not serious enough.

The ex-prosecutor, Air Force Colonel Moe Davis, told a pre-trial hearing for another Guantanamo Bay inmate he had "inherited" the Hicks case and wanted to focus on cases serious enough to merit 20-year jail sentences, with the Australian's case not meeting that mark.

Col Davis also said the commissions were tainted by political influence and evidence obtained through prisoner abuse.

Hicks, from Adelaide, is the only Guantanamo Bay detainee to have his case resolved.

He avoided trial by pleading guilty at a commission hearing at Guantanamo Bay in March last year to providing material support for terrorism.

Hicks was sentenced to seven years' jail with all but nine months suspended under a plea bargain which also secured his return to Australia to serve out the sentence.

He was released from South Australia's Yatala Prison last December.

Hicks father, Terry Hicks, and Australian lawyer David McLeod said today they were not surprised by Col Davis's testimony.

"We have been saying this for quite a long while," Mr Hicks said.

"Most of the evidence was gained under pretty rough treatment and also there was political influence, particularly towards the elections."

Mr McLeod said Hicks was a political pawn from the time he was captured among Taliban forces in Afghanistan in December 2001.

"The whole push to charge him was a political process in itself," Mr McLeod said.

"The only reason that he was charged in the first place was because of political pressure that was brought to bear, probably by the Australian Government.

"But certainly the wash-up of it was completely politically tainted."

Mr Mcleod said "the only reason that David Hicks is in Australia now" was public opinion.

"The Australian Government had become intransigent. Public opinion was the only thing that would make them react," he said.

"Until we got 51 per cent of the people calling for Hicks' return, (former prime minister John) Howard wouldn't budge.

"Once that public opinion dial had gone over the 50 per cent mark, the Australian Government did everything it possibly could, in its view, to push the matter along.

"It was obvious they wanted Hicks off the front page ... it didn't work, it didn't get them re-elected, but it gave them one less fire to put out."

Col Davis made his remarks in a pre-trial hearing for Salim Hamdan, a Guantanamo detainee who was al-Qaeda leader Osama bin Laden's driver.

Col Davis, who quit the war court last year, said the military commissions were tainted by political influence and evidence obtained through prisoner abuse.

He told the hearing pressure was ramped up after "high-value" prisoners with alleged ties to the September 11, 2001, terrorist plot were moved to Guantanamo from secret CIA custody shortly before the 2006 US congressional elections and amid the ongoing US presidential campaigns.