In the early 1990's, Nickelodeon decided to invest in more expensive, yet possibly more lucrative programming. Gone were the Canadian imports and cheap game shows. In their place were costlier cartoons that could produce valuable licensing opportunities. One of the early successes was Doug, which had an unusual production contract- since Nickelodeon didn't have its own animation facilities, it setup Doug's creator Jim Jenkins with his own studio and a promise to pickup 5 seasons of the show. This promise had an unusual clause; if Nickelodeon didn't pickup the agreed upon 5 seasons, Mr. Jenkins could shop the show around to other networks and Nickelodeon would surrender the copyrights and trademarks to the characters, though it would retain ownership of any episodes produced for it.
So how did Doug end up at Disney? Unbelievably, Nickelodeon decided that Doug was too expensive to produce after season 4. Whether they were merely playing hardball or didn't think that Jim Jenkins would find somewhere else to take Doug, they firmly stated that they would no longer have any use for the show. ABC had been circling Jim Jenkins' animation studio after learning that there was a chance it could pick up Doug. When The Walt Disney Company purchased ABC in 1995, many assumed it was game over for Doug, but Disney not only picked the show up, it bought Mr. Jenkins' studio, trademarks and copyrights. A stunned Nickelodeon watched one of its biggest shows walk right out the door.
So Doug now exists in a weird copyright situation. Its first four seasons are owned by Nickelodeon, while the trademarks, copyrights and later seasons are all owned by Disney. While Nickelodeon can show its Doug episodes, it cannot produce any toys or license any merchandise. A weird situation indeed.