The Motion Picture Association of America today said it had given the movie an adult rating because it contained "violent and disturbing images" and strong language.
http://www.news.com.au/common/story_page/0,4057,9846681%255E1702,00.html

The film's distributor, Lions Gate Films, immediately filed an emergency appeal to have the rating reviewed. Lions Gate chairman Tom Ortenberg said in a statement the ratings board's decision was "completely unjustified".

"We are adamant about overturning this decision in an expeditious manner to ensure that as many people as possible ... are able to see one of the most important and thought-provoking films of our time," he said.