Article 7

Article 7 was part of Gallifreyan law and prohibited any form of genocide. The Valeyard accused the the Doctor of this for destroying the only known Vervoids on the Hyperion III. (DW: The Trial of a Time Lord: Terror of the Vervoids; DW: The Trial of a Time Lord: The Ultimate Evil)

The Time Lords, specifically the Celestial Intervention Agency (NA: Lungbarrow, referencing DW: Genesis of the Daleks) had earlier asked the Doctor to commit genocide by, if at all possible, having him to prevent the Creation of the Daleks. (DW: Genesis of the Daleks)