This force was hired to terraform the seemingly uninhabited planet of Aetia. After having his mind opened by the Aetius in his mind, Captain Kybo fled the scene and crash landed in a Victorian circus on the 19 May 1884. There, he was captured, bound in chains and forced to perform, followed closely by the Sixth Doctor, who met a similar fate.
The 19th Judoon Interplanetary Force followed closely behind in order to find Kybo, placing it on a higher priority than the terraforming project. Once they had found him, they took him to a local courthouse to prove him guilty of absconding. Whilst they formed the prosecution, the Doctor formed Kybo's defence.
The Doctor then explained that the planet was, in fact, inhabited by a race that the Doctor named the Aetius. To defend their planet, the Aetius entered the normally small minds of the Judoon, allowing them to admire nature and poetry. Using a DNA scoop, the Judoon brought Meretricious Gedge, one of the crew who hired the Judoon to perform the terraforming. Whilst there, the Doctor proved to the whole galaxy that Gedge knew the planet was inhabited, and the project was immediately cancelled.
At the end of their ordeal, the whole group of Judoon decided to live undercover for the rest of their lives on Aetia rather than taint the Judoon systems with their newfound poetry and understanding of beauty. (AUDIO: Judoon in Chains)