http://en.wikipedia.org/wiki/Torture
Geneva Convention IV exemptions
GCIV provides an important exemption:

"Where in the territory of a Party to the conflict, the latter is satisfied that an individual protected person is definitely suspected of or engaged in activities hostile to the security of the State, such individual person shall not be entitled to claim such rights and privileges under the present Convention [ie GCIV] as would ... be prejudicial to the security of such State ... In each case, such persons shall nevertheless be treated with humanity" (GCIV article 5)
There are two further groups who are not protected by GCIV:

Nationals of a State which is not bound by the Convention are not protected by it.
Nationals of a neutral State in the territory of a combatant State, and nationals of a co-belligerent State, cannot claim the protection of GCIV if their home state has normal diplomatic representation in the State that holds them (article 4). Since nearly every state has diplomatic recognition of every other state, most citizens of neutral countries in a war zone are not able to claim any protection from GCIV.
In a conflict like the U.S. War on Terrorism many so-called "unlawful combatants" have controversially, and contrary to the analysis of International Human Rights organisations, been denied protection under the Geneva Conventions, because they are either excluded by their nationality (see below), or they are deemed to be so dangerous that Article 5 can be invoked, or because they allegedly do not fit the textual description of a lawful combatant (are not members of the armed forces of a Party, do not have uniforms, do not display a "fixed distinctive sign recognisable at a distance").
Bong30 Reviewed by Bong30 on . United States Before the Committee Against Torture For the first time since the Bush administration launched its global campaign against terrorism, the United States this week will answer internationally for its record on torture. On May 5 and May 8, the United Nationā??s Committee Against Torture will question some 30 high-level officials from the Departments of State, Justice, Homeland Security, and Defense on U.S. compliance with the Convention against Torture and Other Cruel Inhuman or Degrading Treatment or Punishment. The U.S. officials Rating: 5