The Name of the Doctor ends with the 11th Doctor confronting a prior version of himself that “broke the promise.”
John Hurt’s “War Doctor” is not the first Doctor to break the promise of doing no harm. The Sixth Doctor did so on two major occasions.
In Trial of a Time Lord, the Sixth Doctor was forced to commit genocide on the Vervoids in order to save others. The species was artificially created and plant-like. Given the fact the Vervoids were intent on killing humans, the Sixth Doctor’s action were justifiable under the self-defense doctrine.
That still does not change the fact the Sixth Doctor had to kill all of them.
The Two Doctors might the only time the Doctor killed someone with his bare hands.
The Sixth Doctor killed the Androgum Shockeye with cyanide-soaked cotton wool used to kill butterflies (which belonged to an actor that Shockeye killed). This was done after the Doctor was injured and pursued by Shockeye with knife. While the Sixth Doctor killing Shockeye would be justified as self-defense against someone trying to use lethal force, it is possibly the only time the Doctor personally killed someone.
He usually just leaves a bad guy to die.
How Not to Play Doctor
Dastari from the Chimera space station performed medical experiments Androgum to “improve” them. Dastari also infused the Second Doctor with Androgum to change him into an Androgum/Time Lord hybrid against the Second Doctor’s will.
Medical experimentation on human beings requires informed consent of the patient. See, Cal Health & Saf Code § 24175.
California’s legislative intent for regulating medical experimentation on human beings is to “protect the rights of the human subjects involved.”
Moreover, the statute is to make the Nuremberg Code of Ethics in Medical Research developed after the trial of Nazi war criminals for unethical use of persons in medical experiments and the Declaration of Helsinki established recommendations guiding doctors in experimentation involving human subjects actually enforceable. Cal Health & Saf Code § 24171 (2013).
Dastari ignored these principles in his experiments on the Second Doctor, Shockeye and likely other Androgum victims who did not offer their informed consent. While none of them were human beings, they were sentient life forms that would fall under the intent of the law’s purpose to protect life.
He’s The One Who Broke the Promise
We will learn exactly how the War Doctor broke the promise on The Day of the Doctor. However, given the fact there was a universal war with both sides committing atrocities, the War Doctor’s actions likely were justified.
Too bad the War Doctor’s actions only successfully killed off every Time Lord, leaving the Daleks to return.