The committee has 59 questions for the US, 53 of which relate to the war on terror.
Officials will be asked to provide a list of all secret detention centres, nationalities and numbers of those being held and the reasons for their detention. The committee will also ask for details of detainees taken abroad to third countries, in a process known as extraordinary rendition.
It wants to know what measures the US has taken in the wake of the Abu Ghraib scandal to ensure that such abuse does not happen again.
They may also want to know if there has been an independent inquiry into the possibility that high-ranking government officials authorised torture.
Human rights campaigners say the hearings have huge significance.
"What makes this so remarkable is that this is the first time the United States is accountable for its record on torture with regard to some of the practices implemented after 9/11," said Jennifer Daskal of Human Rights Watch.
Ten legal experts will cross-examine the US team until Monday and the committee will publish its recommendations at a later date.
The US is obliged by the UN convention to implement the recommendations, although there is no enforcement mechanism.