Justicia is a solar system which is used as a massive prison.
History
Justicia was originally formed to store alien criminals, but due to overcrowding amongst the EarthGov colonies, Human criminals were also sent to Justicia.
Around the 2500s, the Blathereen discovered another use for Justicia. The position of its planets made it suitable for warp-holes, which they could use to transport the entire system and use the suns as means to destroy planets, giving them a supply of spaceship fuel. They slowly replaced people of power and lead the research section of Justice Gamma to figure out the necessary math. In 2501, the Doctor and Rose arrived on Justice Alpha and were arrested. The Doctor's skills meant the project could be pushed forward, but the meddling of the Doctor, Rose and three Slitheen lead to the eventual failure of the project and the destruction of the Blathereen criminal empire. (NSA: The Monsters Inside)
The system
Justicia was located near the edge of the Mutter's Spiral, far away from Earth. There were auto-beacons warning all ships which come within two light years and a deflection barrier which extends 10 billion miles. It has three suns and 6 planets with nearly circular orbits. (NSA: The Monsters Inside)
Planets of the System
Justice Alpha
Justice Alpha is a muddy planet which is 100 million miles from the suns and the first planet in the Justicia system. It was also the planet on which Rose Tyler and the Doctor arrived and the location of their capture. It had a green sky and had a lower gravity then Earth. It was used for historical re-enactments, such as pyramid building. The Blathereen planned to store the processed fuel here.
Justice Beta
Justice Beta was covered in greenish marshes and low tech prisons, constructed as a test and used for the confinement of Human criminals, specifically juvenile delinquents. It was 150 million miles from the suns. This was where Rose is sent after being captured on Justice Alpha. The Blathereen planned to use it for breeding stock.
Justice Gamma
Justice Gamma had a Middle Eastern jail colony where Human prisoners are kept. They had a wide variety of experiments done on them. It is 200 million miles from the suns. The Blathereen planned to use this planet for heavy labour.
Justice Delta
Justice Delta was a forested planet with a green sky. The Executives lived on Justicia Delta and controlled Justicia from there. Ecktosa and Dram were both caught here trying to find the antique Compression fields. It was taken over by the Blathereen during the plot and used as a home base.
Justice Epsilon
Justice Epsilon had acid plantations. Dennel's father was sent here for bank robbery. The Blathereen planned to use this planet for processing the remains of the destroyed planets.
Justice Prime
Justice Prime was a small and cold planet, so cold that the nitrogen on the surface was turned into snow as it moved away from the sun. It was the only planet in the Justicia system not to have a circular orbit. This planet was the first to be used as a prison planet, specifically for alien criminals. The criminals are kept underground in the SCAT-house (Species-lead, Creative and Advanced Technologies). It is here that the Doctor was sent after being captured on Justice Alpha.