Bush and Rumsfeld sidestepped the Geneva Convention in their "war on terror", civilian defence counsel Paul Bergrin said on Monday.
He was speaking to reporters after an impassioned address in the courtroom on the first day of initial hearings being held in Baghdad this week for three US soldiers facing abuse charges.
Bergrin has however won permission to seek testimony from the top US general in Iraq, Lieutenant General Ricardo Sanchez and from the chief of the US Central Command, General John Abizaid.
Bergrin said his client, Sergeant Javal Davis, was instructed on a daily basis to soften up Iraqi prisoners to obtain intelligence.
"Bush gave a speech declaring his war on terror and said the Geneva Convention no longer applied," Bergrin told reporters after an impassioned address in the courtroom.
He accused Rumsfeld and other top US officials of trying to redefine the definitions of abuse and torture in a campaign aimed at influencing lawyers at the Department of Justice.
Pretrial hearings are being held in Baghdad this week for Davis, Specialist Charles Graner and Staff Sergeant Ivan Frederick, reviving notorious images of sexual and physical humiliation that sparked worldwide outrage.
Ghraib - a crime scene
The presiding judge Colonel James Pohl, has declared the prison a crime scene and said it could not be destroyed until the case is adjudicated.
The photographs of smirking American soldiers tormenting naked detainees rocked the US military when they emerged in April, prompting claims that policies adopted in President George Bush's "war on terror" had encouraged the cruelty.
A sketch of Davis (R) and his
defence lawyer Paul Bergrin
The US army has launched investigations into seven low-ranking suspects in relation to abuse at Abu Ghraib.
Two of the three suspects to appear on Monday face charges over abuses depicted in some of the most widely circulated images - including a human pyramid of naked detainees, a woman soldier holding a detainee on a leash and a hooded man standing on a box trailing wires from his wrists.
The Abu Ghraib prison in Baghdad was infamous under ousted dictator Saddam Hussein as a place where his opponents were tortured, lending extra symbolism to images of abuse by US troops.
The start date for the three soldiers' court martial has not been set, but may be announced by Pohl, after the hearing which began on Monday, and may last several days. All three suspects have yet to plead.
The hearing in the US-led administration's Green Zone headquarters may deal with little more than routine procedural matters, but might confront more significant issues such as any possible disputes over evidence, a US army officer said.
The US military has conducted at least 80 courts martial in Iraq since last year's invasion, on charges ranging from theft or assault to involuntary manslaughter, the officer said.
Graner, who faces the most serious accusations, could be sentenced to up to 24 years and six months in jail if convicted of various charges.
Graner faces most serious charges,
including the taking of this picture
He is accused of photographing a detainee being dragged by Private First Class Lynndie England on a leash, and posing for a picture by a pile of naked detainees in November, the date when most of the alleged abuses took place.
Graner is also charged with forcing prisoners to strip naked and masturbate in front of each other, and forcing one detainee to simulate oral sex on another, before taking a picture.
Frederick faces charges including participating in an incident where a prisoner was hooded and made to stand on a box with wires attached to him, and told he would be electrocuted if he fell off - an image splashed on front pages worldwide.
Davis faces charges including jumping on a pile of detainees and stamping on prisoners' hands.
One US soldier, Specialist Jeremy Sivits, was sentenced to a year in prison in May after pleading guilty at a special court martial to abuse charges. England is expected to learn this month if she is to be court martialled.