Level 5 planet
A Level 5 planet, also called a level 5 civilisation, 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, and as such were protected by various Galactic Laws. (TV: Smith and Jones, Partners in Crime, The Eleventh Hour) The designation derived from socioenergetics, with other designations including levels 1, 2, 4, and 6 planets.
Romana II stated that level 5 planets were notoriously bad at long-term planning, in regards to ecology. (AUDIO: Legacy of Death
While a level 2 planet in the 1940s, (PROSE: Ghosts of India) Earth became a level 5 civilisation by 1957, (PROSE: First Frontier) remaining at that status through 1979, (TV: City of Death) 2008, (TV: Voyage of the Damned, Revenge of the Slitheen, The Eleventh Hour) 2009, (TV: Partners in Crime) 2016, (PROSE: What She Does Next Will Astound You) and into 2040, (AUDIO: Phantoms of the Deep) although Romana I once referred to Earth in 2011 as having a level 4 civilisation. (AUDIO: Ferril's Folly)
Aoris was a level 5 planet in Era 24 of its history. (AUDIO: The Paradox Planet)