Why the hell is De Niro billed first!?

You can have your criticism about this film but they did succeed in communicating the moral: RACISM IS BAD!

But when the movie ended, I quickly noticed something awkward. Robert De Niro's name appeared on top of the credits, followed by Cuba Gooding jr. It's funny because I didn't get the impression that De Niro had a bigger part, nor that the film was about his character. It's as if the theme of the film reflected itself on the production: The black guy not getting the recognition for his greater effort.

There are a couple of other films where De Niro get's billed first while clearly not playing the main character. I noticed that in Mean Streets and Goodfellas. Maybe it's all part of his contract or maybe his name means "He who get's billed first".