Several times, in the new series, the Doctor has said that he can't go back and change things or encounter people out of sequence in their timeline. (River Song being the exception.)

Usually the Doctor doesn't worry about rules, feeling like he often knows better than those who make the rules, but he's very strict with this one. Is this just what he knows from experience, or is there an actual Timelord law or rule that governs this behavior? Or is it just such a blindingly stupid thing to do that there's no need for such laws or rules? Or his is strict adherence to this a result of personal experiences that happened before the newer series?

  • I may have not phrased my own question right, but are we asking the same question: scifi.stackexchange.com/questions/10162/…
    – HNL
    Commented Feb 2, 2012 at 7:56
  • They could lead to different answers. If people want to close this, that's fine, but I suspect (and am not sure) that this may result in the answers going on a different tangent. (But I've been wrong before!)
    – Tango
    Commented Feb 2, 2012 at 8:35
  • Considering that the Doctor is more than happy to travel along his own timeline when it is extremely convenient for him to do so, I would say that this is something he made up to keep companions from asking to change their own past.
    – Xantec
    Commented Feb 2, 2012 at 13:31
  • @Xantec: That's what I thought. But he also doesn't go back and alter things that might save lives. (On the other hand, how much of that can he do without having to do it repeatedly in some situations?)
    – Tango
    Commented Feb 2, 2012 at 17:40
  • 1
    As the Doctor doesn't read history, he likely does not re-do anything that he's already done for fear of making the outcome worse. He already saves a lot of people as it is.
    – Xantec
    Commented Feb 2, 2012 at 17:44

1 Answer 1


I doubt there is actually any hard law about a Timelord changing things that have occured in his own or a companion's timeline. At least, by the time of the ninth and tenth Doctors there is no one to up hold such a law. More likely The Doctor loosely lives by this sort of rule to prevent paradoxes, as well as to keep from potentially making any situation worse than it was when he started/left.

Take for example the companion Rose Tyler. The Doctor agreed to take Rose to witness her father's death. Not just once even, but twice. The second time of course Rose breaks time and paradoxes ensue. I can not recall any episodes after this in which The Doctor took a companion across their own past timeline, so perhaps this was when The Doctor decided doing this was a bad thing (for humans at least).

However, The Doctor himself has been happy enough to cross his own time as it suits him, or when he is desperate enough. In the first episode with Martha Jones the tenth Doctor crosses his own timeline to visit Martha on the street before she meets him in the hospital. Another example, in The Big Bang The Doctor crossed his own path in the museum. This was rather dire circumstance with the fate of the universe on the line, after which the universe was rebooted and any damage to time was effectively re-written.

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