Scores of lawyers representing Iraqis are going to the High Court seeking an "independent" public inquiry into allegations that British interrogators were guilty of the systemic abuse of civilians in Iraq.
Lawyers for the Iraqis allege there were a number of unlawful killings as well as incidents of torture from March 2003 to December 2008 in British-controlled detention facilities.
Defence Secretary Philip Hammond plans to investigate the claims through the Iraq Historic Allegations Team (IHAT), which includes members of the Royal Navy Police (RNP).
Public Interest Lawyers (PIL), who are acting on behalf of 192 Iraqis, are seeking judicial review on the grounds that the RNP lack sufficient independence as numerous Royal Navy officers were involved in interrogations with the UK Joint Forward Interrogation Team (JFIT).
PIL said a number of unlawful killings and cases of inhuman and degrading treatment were linked to JFIT's activities as interrogators sought to extract information.
They argue justice requires a fully independent public inquiry.
Two judges sitting in London will hear accusations that civilians were subjected to a number of techniques to disorientate and debilitate them, including deprivation of sleep, food and water.
Sir John Thomas (President of the Queen's Bench Division) and Mr Justice Silber will be told there was also hooding, forced nudity, sexual humiliation and repeated and lengthy interrogations.
The three-day application is the second legal challenge in a case in which PIL say there was systemic abuse, as opposed to ill treatment by "a few bad apples".
Ministry of Defence lawyers are opposing the application, saying any acts that have been proven were in isolation.
British soldier Corporal Donald Payne was jailed in 2006 after he was filmed shouting at detainees who were hooded and being held in stress positions.
An MoD spokesman recently said: "The IHAT is the most effective way of investigating these unproven allegations rather than a costly public inquiry."