Level 5 planet
From Tardis Wiki, the free Doctor Who reference
A Level 5 planet was a designation used by Galactic Law in reference to certain worlds, with the implication that it referred to relatively primitive planets not yet fully integrated into galactic civilisation. Level 5 planets were protected by various Galactic Laws.
Known Level 5 Planets
- Earth, as of 1979 and 2008. (TV: City of Death, Voyage of the Damned, Partners in Crime, The Eleventh Hour, Revenge of the Slitheen)