In a rare move for a TV show, FOX has absolutely no control over episodes of The Simpsons

Many shows are limited in the material they can broadcast by the network they are on, yet the TV show, “The Simpsons,” is not one of them. Networks like to have control over the shows they air so they can ensure no material is inappropriate or will put off viewers, but in the case of “The Simpsons” producers were able to negotiate a specific contract in which FOX could not make decisions or cuts to episodes.

The reason the show was able to negotiate this was because FOX was struggling as a TV network when “The Simpsons” signed on. Because they did not have large viewership they were desperate to get different shows to join their network, and so they allowed “The Simpsons” to air their episodes almost independently of FOX. This provision also allowed the show to make fun of FOX, which most other shows can’t do that easily! 

(Source)