Anas al-Libi is widely believed to be in military custody aboard a US warship in international waters following his capture over the weekend in Libya.
He was indicted in 2000 over the 1998 bombings of two US embassies in East Africa.
While the US is offering assurances that al-Libi will be treated humanely, human rights advocates say the terror suspect could still be subjected to treatment that amounts to torture.
After the Bush administration was found to have tortured prisoners with techniques such as waterboarding, President Barack Obama was keen to assure the world that those days were over.
No longer would the US capture people in foreign countries and fly them to other nations for questioning in secret prisons where they were tortured.
It was a practice known as extraordinary rendition.
Laura Pitter is the counter-terrorism advisor at Human Rights Watch in New York.
"It was clear that the people being picked up and detained around the world were being sent to US run detention centres where they were being tortured and two to other countries for the purposes of torture, that is very different from what is happening now where there's clearly a criminal indictment pending and the administration has made clear that those so called enhanced interrogation techniques are not being used but they do have to do a better job of ensuring that was is allowed under the Obama administration is not used in a way that does amount to torture."
And the reason the US interrogators need to be careful, says Laura Pitter, is because the techniques in and of themselves are not defined as torture but if they're used in combination they are.
"Well I think you do have to credit the administration for making clear that the enhanced interrogation techniques that were used in the previous administration are not no longer legal, they're no longer authorised but in combination certain things that are now authorised under the Obama administration can constitute torture so they have to do a better job of narrowing what is permissible and making sure that when sleep deprivation and, you know, sensory deprivation, these things that are permitted that they are not used in combination to a degree that can amount to torture."
Speaking in Washington, President Obama is already satisfied that al-Libi is guilty.
"We know that Mr Al Libi planned and helped execute plots that killed hundreds of people, a whole lot of Americans and we have strong evidence of that and he will be brought to justice."
Professor Donald Rothwell from the Australian National University says while al-Libi is being detained at sea in international waters, he's not entitled to access to a lawyer.
"Because he's considered to be a combatant he doesn't have those rights in the same way that one would have in a civilian setting if one was detained by law enforcement officials within a country so he's being held in a military setting, he of course would know that as a prisoner being held in a military setting there is limited information he can legitimately be expected to give but that beyond that he's not entitled to legal representation or legal assistance because of the circumstances under which he's been held so this is, if you like, another one of the these grey areas where the United States can exploit that given the circumstances under which Al Libi is being held at this point in time."
Laura Pitter from Human Rights Watch says al-Libi should be granted legal representation as soon as possible.
"Well from Human Rights Watch perspective he is facing a criminal indictment, he's been held incommunicado detention in an undisclosed location and he needs to be presented before a judicial authority, informed of the charges against him and have access to a lawyer."
Libya is furious with the US and is demanding al-Libi be returned to Tripoli.
Justice Minister Salah al-Mirghani held a news conference after calling in the US ambassador for an explanation.
"We have made it clear to the US government that this is an act of kidnap of a Libyan citizen that does not comply with Libyan law, and the US government reply from the Ambassador was that it was about implementation of a court order."
