The UK government is accused of misleading the High Court to prevent a full public inquiry into allegations of abuse by British troops in Iraq.
Human rights lawyers with the Public Interest Lawyers (PIL) made the claim after the High Court granted Ali Zaki Mousa and 142 others permission to appeal against its previous ruling that they were not entitled to a public inquiry into whether they were abused by British troops.
The High Court heard that some 222 Iraqi civilians have been the victims of "systemic abuse," including torture, inhumane and degrading treatment, at the hands of British troops and interrogators in Iraq.
The PIL first lodged the initial claim for judicial review of the government's refusal to establish an independent probe into the claims of "systemic" brutality in February last year.
Former defence secretary Bob Ainsworth successfully argued in November that an ongoing investigation by the Iraq Historic Allegations Team (IHAT) was sufficient.
PIL argued that IHAT was not sufficiently independent due to the involvement of the Royal Military Police (RMP), which had worked closely with troops, in the body.
The High Court at the time accepted the government's counter argument, set out in a statement from RMP Deputy Provost Marshall Colonel Prosser.
Col Prosser told the court that although the General Police Duties section of the RMP had worked closely with troops, the RMP involvement in IHAT was from the Special Investigations Branch, which had played a different role.
After the court found in favor of the government, PIL said that Defence Secretary Liam Fox has "extraordinarily" written to the court saying that in fact IHAT has comprised 13 Special Investigations Branch members and 32 members of the General Police Duties.
"The point was not specifically raised by those who understood the detailed arrangements, because to them it was clear that a major and complex Special Investigations Branch investigation always involves some support from the General Police Duties and they assumed that that would be known to and understood by those presenting the case," he wrote.
In granting permission to appeal, the High Court said that the case "is of sufficient importance to merit the attention of the Court of Appeal, especially on the question whether IHAT is sufficiently independent."