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.[source needed]

Earth is a Level 5 planet. (TV: Voyage of the Damned)

Known Level 5 Planets