Non-interference policy

The policy of non-interference was fundamental to Time Lord attitudes towards and dealings with the rest of the universe.

Origin
Following the Time Lord-Vampire War, the Time Lords had abandoned the use of violence, but continued to involve themselves in the affairs of the wider universe. This had catastrophic results for the people of the planet Minyos who were gifted with high technology by the Time Lords, whom they regarded as god-like beings.

As a result of being granted technology they did not have the cultural maturity to use responsibly, nuclear war broke out on Minyos and the Minyans were nearly made extinct. The Time Lords were driven from Minyos at around the same time.

Horrified by the results of their meddling, the Time Lords adopted a strict policy whereby they would only observe the events of the wider universe, and never become involved personally. (DW: Underworld)

Consequences & Exceptions
It was partly the non-interference policy which led to the Doctor leaving Gallifrey: he claimed he was bored there and wanted to experience the universe first hand. When the Time Lords eventually located him he was put on trial for breaching the policy. (DW: The War Games)

Like many of their principles, the Time Lords' attitude to the non-interference policy was somewhat flexible, even to the point of hypocrisy. Even before the Doctor's departure he was able to make the Time Lords implement a ban on miniscopes, an act which earned him great respect in the wider universe. It was the Time Lord Irving Braxiatel who organised the Armageddon Convention, which led to the banning of many weapons of mass destruction amongst leading civilised species. (DW: Carnival of Monsters, MA: The Empire of Glass)

Rather oddly, the Time Lords punished the Doctor for repeatedly involving himself in the affairs of less-advanced planets by involving him in the affairs of a less-advanced planet for an extended period of time: they exiled him to Earth in the 20th century with his TARDIS rendered inoperative.

In any case, the Time Lords repeatedly demonstrated a willingness to involve themselves in the affairs of the universe, using the Doctor as an unofficial (and frequently unwilling) agent. For a considerable period of time they used his talents to further their own agenda:


 * The Second Doctor appears to have carried out a series of missions for the Time Lords between the end of his trial and his actual regeneration. (DW: The Two Doctors, PDA: World Game, etc)
 * The Time Lords sent the Doctor to Uxarieus to stop the Master gaining control of the Doomsday Machine, to Solos to help the natives complete their natural metamorphosis, and (probably) to Peladon to help the planet's bid to join the Galactic Federation. All of these occurred prior to the formal lifting of the Doctor's exile. (DW: Colony in Space, The Mutants, The Curse of Peladon)
 * Following the lifting of the exile it was harder to tell which of the TARDIS' unplanned landings were a result of Time Lord intervention and which were simply caused by poor piloting. The Time Lords certainly appear to have helped the Doctor pursue the Daleks to Spiridon. (DW: Frontier in Space, Planet of the Daleks)
 * A Time Lord appeared to the Doctor in person at the start of his mission to Skaro to avert the creation of the Daleks (a mission to ultimately have dire consequences for the Time Lords). (DW: Genesis of the Daleks)
 * The Doctor believed his arrival on Karn was the result of Time Lord interference. The presence on the same planet of the remnants of the renegade Morbius would seem to suggest he was correct. (DW: The Brain of Morbius)
 * Much later, the Doctor believed his involvement in the Cybermen's attempt to destroy Earth in 1985 was a result of Time Lord machinations, although there was little evidence to support this. (DW: Attack of the Cybermen)

Most of these missions seem to have taken place under the auspices of the Celestial Intervention Agency, a shadowy Gallifreyan faction who took a particular interest in the Doctor. (DW: The Deadly Assassin)

The full extent of the CIA's activities were unknown, and individual Gallifreyan attitudes to the policy varied - Rodan appeared to regard it as inviolable, whereas Romana showed no surprise after being asked to leave Gallifrey and assist the Doctor. (DW: The Invasion of Time, The Ribos Operation)

The Time Lords later breached the policy on a major scale themselves: after Andromedans based on Earth were able to infiltrate the Matrix and steal its secrets, they devastated the planet and moved it light-years across space to conceal what they had done and prevent the secrets reaching Andromeda. They also manipulated events and individuals on Thoros Beta to prevent Crozier from discovering an effective means of immortality. (DW: The Mysterious Planet, Mindwarp)

The Doctor discovered what had happened to Earth but was unaware of the reasons why. Apparently fearing his reaction, the Time Lords put him on trial for his life, the initial pretext being (ironically enough) his repeated breaches of the policy. (DW: The Trial of a Time Lord)

Despite the attempts of the Time Lords to conceal their involvement by using the Doctor as an agent, the Daleks eventually learned of the attempt to have their creation averted. This was apparently one of the causes of the Last Great Time War and the near-total extermination of the Time Lords as a species.