The US should name a special prosecutor to look at Donald Rumsfeld's possible role in the abuse of US military prisoners, a human rights group says.
Donald Rumsfeld is already being sued over abuse claims
Human Rights Watch says the US defence secretary may bear "command responsibility" for abuse in Iraq.
The organisation says others, like former CIA director George Tenet, should also face investigation.
Meanwhile, the former commander of US troops in Iraq, Ricardo Sanchez, has been cleared of the Abu Ghraib abuses.
The Pentagon says Mr Rumsfeld did not authorise or condone any abuse.
Human Rights Watch (HRW) released its report ahead of the first anniversary of the Abu Ghraib scandal, which broke in late April last year.
It emerged that US guards at the Baghdad prison had subjected Iraqi detainees to torture and abuse.
Some guards have gone on trial but critics say there has been no full investigation into what senior defence figures knew about or even authorised.
"The soldiers at the bottom of the chain are taking the heat for Abu Ghraib and torture around the world while the guys at the top who made the policies are going scot free," said Reed Brody, special counsel for HRW.
Since Abu Ghraib, the Pentagon has also opened dozens of investigations into alleged abuse of prisoners in Iraq and Afghanistan, while allegations persist about mistreatment at the US military base at Guantanamo Bay in Cuba.
HRW said Mr Rumsfeld could be liable for war crimes under the doctrine of "command responsibility" - the legal principle that holds a superior responsible for his subordinates' actions when he knows, or should know, that crimes are being committed but fails to stop them.
It said Mr Rumsfeld approved interrogation techniques - such as the use of guard dogs to frighten prisoners and painful "stress" positions - that violated the Geneva Conventions.
It said the investigation should not be carried out by justice department officials because Attorney General Alberto Gonzales himself had a role in approving interrogation techniques.
It called on Congress and the president to establish a special commission and appoint a special prosecutor.
HRW says it has "substantial evidence warranting criminal investigations" into Mr Rumsfeld, Mr Tenet, Lt Gen Ricardo Sanchez and Gen Geoffrey Miller, former commander of the prison camp at Guantanamo Bay.
But a new inquiry announced on Friday it had found no evidence of wrongdoing by Gen Sanchez and three top collaborators.
Gen Sanchez authorized tougher interrogation techniques in September 2003, but the inspector general who led the investigation listed mitigating circumstances that allegedly justified his conduct.
Mr Rumsfeld is already being sued by two civil liberties groups on behalf of eight men who claim to have been abused by US forces in Iraq and Afghanistan.
A Pentagon spokesman said HRW's allegations were "frivolous and unsubstantiated".
Lt Cdr Flex Plexico said US policy requires that all detainees be treated humanely and that any credible allegations of illegal conduct are investigated.
"There is nothing in the detention or interrogation policies established by Secretary Rumsfeld or the defence department that even remotely qualifies as torture," he told the BBC News website.
"Secretary Rumsfeld has repeatedly condemned any abuse or mistreatment of detainees."