Gallifreyan law was the legal system on Gallifrey.
Article 17 was a "guarantee of liberty"; part of it affirmed that no candidate for presidency could in any way be debarred or restrained from presenting his claim. The guarantee did not extend to condemned murderers. (TV: The Deadly Assassin)
A "Class One Intervention" was when a Time Lord materially affected the physical properties of a planet, such as its axial rotation. A "Class Two Intervention" was when a Time Lord set themself up as a god in another culture. (AUDIO: False Gods)