"Rumsfeld bears direct responsibility" because he "personally signed off" on policies guiding prisoner treatment, said American Civil Liberties Union Executive Director Anthony Romero.
A number of other lawsuits also are pending against Rumsfeld, military commanders and civilian contractors in the abuse scandal, which broke last spring with the disclosure of photographs showing American military men and women abusing prisoners at Iraq's Abu Ghraib prison.
In response, the Pentagon issued a statement denying "...any assertion or implication that the Department of Defense approved of, sanctioned, or condoned as a matter of policy detainee abuse. No policies or procedures approved by the Secretary of Defense were intended as, or could conceivably have been interpreted as, a policy of abuse, or as condoning abuse."
An independent commission agreed in August 2004 that Rumsfeld and other top Pentagon leaders contributed to an environment in which prisoners suffered sadistic abuse at Abu Ghraib. The members also concluded that the officials could be faulted for failed leadership and oversight.
On Monday the U.S. military to lead an investigation into abuse allegations at the U.S. prison camp at Guantanamo Bay, Cuba.
At a Washington news conference, the ACLU and Human Rights First said the suit was filed in Rumsfeld's home state of Illinois and alleged the eight men suffered physical and psychological injuries while incarcerated in U.S. detention facilities in Iraq and Afghanistan.
In the suit, the two groups said the men were subjected to torture and other cruel and degrading treatment while in the facilities, including severe and repeated beatings, cutting with knives, sexual humiliation and assault, mock executions, death threats, and restraint in contorted and excruciating positions.
The ACLU has also filed three similar complaints against Colonel Thomas Pappas, Brigadier General Janis Karpinski and Lt. General Ricardo Sanchez on behalf of detainees who were allegedly tortured in Iraq. The three additional complaints were filed in federal courts in Connecticut, South Carolina and Texas.