The allegation by doctors with expertise in prison experimentation and torture that the Bush administration conducted "illegal and unethical human experimentation and research" on detainees while in CIA custody after 9/11 is certainly newsworthy. See this, this and this.
Specifically, Physicians for Human Rights - an international doctors' organization - alleges that:

High-value detainees captured during the Bush administration's "war on terror," who were subjected to brutal torture techniques, were used as "guinea pigs" to gauge the effectiveness of various torture techniques, a practice that has raised troubling comparisons to Nazi-era human experimentation.

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"Health professionals working for and on behalf of the CIA monitored the interrogations of detainees, collected and analyzed the results of [the] interrogations, and sought to derive generalizable inferences to be applied to subsequent interrogations," said the 27-page report, entitled "Experiments in Torture: Human Subject Research and Evidence of Experimentation in the 'Enhanced' Interrogation Program." "Such acts may be seen as the conduct of research and experimentation by health professionals on prisoners, which could violate accepted standards of medical ethics, as well as domestic and international law. These practices could, in some cases, constitute war crimes and crimes against humanity."

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For example, CIA medical personnel obtained experimental research data by subjecting more than 25 detainees to individual and combined torture techniques, including sleep deprivation and stress positioning, as a way of understanding "whether one type of application over another would increase the subjects' susceptibility to severe pain," the report said, adding that the information derived from that research informed "subsequent [torture] practices."

If the allegations are true, such experimentation would certainly violate the Nuremberg Code, the Geneva conventions, and the War Crimes Act of 1996.
Nuremberg Code
Among other things, the Nuremberg Code prohibits experimentation conducted without the voluntary consent of the subject. Voluntary consent means:

The person involved should have legal capacity to give consent; should be so situated as to be able to exercise free power of choice, without the intervention of any element of force, fraud, deceit, duress, over-reaching, or other ulterior form of constraint or coercion; and should have sufficient knowledge and comprehension of the elements of the subject matter involved as to enable him to make an understanding and enlightened decision. This latter element requires that before the acceptance of an affirmative decision by the experimental subject there should be made known to him the nature, duration, and purpose of the experiment; the method and means by which it is to be conducted; all inconveniences and hazards reasonable to be expected; and the effects upon his health or person which may possibly come from his participation in the experiment.

Moreover, the Code requires that the subject be allowed to stop the experiment at any time "if he has reached the physical or mental state where continuation of the experiment seems to him to be impossible."
The Code also requires that "the experiment should be so conducted as to avoid all unnecessary physical and mental suffering and injury."
Here, the experimentation did not seek consent at any point. And - rather than limiting pain - the experimentation was specifically conducted as a way to determine how to maximize the pain the subject would experience.
Geneva Convention and War Crimes Act
The Geneva Conventions prohibit torture, mutilation or humiliating and degrading treatment. For example, the Fourth Geneva Convention prohibits:

(a) violence to life and person, in particular murder of all kinds, mutilation, cruel treatment and torture; [or]

(c) outrages upon personal dignity, in particular humiliating and degrading treatment

And the War Crimes Act of 1996, a federal statute set forth at 18 U.S.C. § 2441, makes it a federal crime for any U.S. national, whether military or civilian, to violate the Geneva Convention by engaging in murder, torture, or inhuman treatment. The statute applies not only to those who carry out the acts, but also to those who ORDER IT, know about it, or fail to take steps to stop it. The statute applies to everyone, no matter how high and mighty. Indeed, even the lawyers and other people who aided in the effort may be war criminals; see also this article, this one, and this press release.
The detainees were obviously subjected to mutilation, cruel treatment, torture, and humiliating and degrading treatment, and so both the Convention and the War Crimes Act were violated.
The Bigger Picture
But it is important to keep the medical experimentation story in context.
The bigger picture is that torture doesn't work, it reduces our national security, and it is mainly used to extract false confessions and as a form of intimidation to squash dissent.
Don't believe me?
Okay, then don't read this (and whatever you do, don't click through to look at the links!)