The US government has widened its definition of torture, the justice department announced on its website.
The definition was criticised after revelations of abuses in Iraq
It has retracted its previous assertion that the practice has to involve excruciating and agonising pain.
The new memorandum outlines a definition of torture that could include lasting mental anguish as well as physical suffering.
It also no longer says that the president has the power to supersede anti-torture laws in wartime.
It omits another previous assertion that US personnel have several legal defences against criminal liability in some torture cases.
"Torture is abhorrent both to American law and values, and international norms," the new document says.
The government's previous definition was attacked by some US politicians and human rights groups following allegations of US abuses at the Abu Ghraib prison in Iraq.
They said the definition did not set an adequate barrier to human rights violations.
The US government has opened a number of investigations into allegations of prisoner abuse and detainee deaths in Iraq.