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 civilization. Seeding on a Level 5 planet is prohibited by Galactic Law. (DW: Partners in Crime)
Known Level 5 Planets
- Earth, circa late 20th century and early 21st century. (DW: City of Death, Voyage of the Damned, Partners in Crime, The Eleventh Hour (TV story)", SJA: Revenge of the Slitheen)