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. (TV: Smith and Jones, Partners in Crime, The Eleventh Hour)
Earth, as of 1979, 2008 and 2040, was a Level 5 planet. (TV: City of Death, Voyage of the Damned, Partners in Crime, The Eleventh Hour, Revenge of the Slitheen. COMIC: Snowball!, AUDIO: Phantoms of the Deep)
