The movie was racist: All the black jurors were assholes.
The jury was very diverse: white, black, yellow. But the movie depicted blacks as either arrogant or lazy:
The male black juror kept saying: I don't care about evidence, all I want is to put the defendant in jail, even though all the evidence says otherwise. (A prick.)
The female black juror kept saying: I don't care about whether the defendant is guilty or not, all I want is to go back to my home to take care of my children. (A lazy pig.)
All the assholes were black, on the other hand, white and yellow are depicted as smart: the white cop was very careful about his duty as jury, and the asian was a doctor.