LOS ANGELES — When the Motion Picture Association of America voted to uphold the R rating for "Bully" several weeks ago, the documentary's distributor, Harvey Weinstein, kicked up a dust storm of protest and publicity. But it's not just Weinstein keeping the appeals board busy this year — the group is facing a significant increase in the number of filmmakers seeking to overturn the initial ratings for their movies.

The MPAA, which administers the ratings system via its Classification and Rating Administration, has already heard eight appeals for films scheduled for release this year. That's double the number the group heard for movies released in 2011 and surpasses the seven appeals it heard for 2010 films.

The MPAA is a trade organization composed of the six major Hollywood studios, but most of the appeals are from companies that are not members of the group: Seven of this year's appeals came from smaller studios and distributors such as the Weinstein Co., Lionsgate and Relativity Media.

The 2012 appeals vary widely — they have concerned movies such as the action adventure "Sea Level," which tried (unsuccessfully) to nab a G rating, and a raunchy crime drama, "Killer Joe," which sought (also unsuccessfully) to be downgraded to R from the adults-only NC-17. Collectively, though, the appeals speak to a growing trend in which distributors and the MPAA fail to see eye-to-eye on ratings.

"I think studios are starting to push a little harder," said Ethan Noble, who runs Motion Picture Consulting, a company that assists filmmakers and studios with ratings and who has worked on numerous appeals, including the one for "Bully." "And while I think that this is the best system we can have, there does seem to be a disconnect between what the ratings board wants and what filmmakers think should be allowed."

That disconnect, say Noble and others, comes from changing social mores about language and other areas of explicit content while the MPAA, Noble said, is "basically using the same system it's had in place for years."

Some but not all of the recent appeals have centered on language. Because the potential audience for PG-13 movies is bigger than that of R-rated ones, filmmakers have an economic interest in a less restrictive rating.

Though more ratings are being appealed, the MPAA is showing little inclination to reconsider its rulings. All but one of the appeals for 2012 movies failed in their bid for a lower rating; the one successful appeal was for Lionsgate's high-school romance "The Perks of Being a Wallflower," which was changed from an R to a PG-13. By contrast, nearly 50 percent of appeals were successful in 2010 and 2011.

In a statement, Classification and Rating Administration chief Joan Graves said, "As the numbers indicate, the frequency of appeals simply varies from year to year. The bottom line is that around 700 films are reviewed for ratings each year and rarely does the number of appeals even reach double digits." She pointed to three years in the past decade — 2003, 2004 and 2007 — when they hit that mark.

The initial ratings are assigned by a group of paid MPAA employees. The trade organization refuses to identify its raters but says they are parents; last year, the MPAA rated 758 movies.

The appeals panel is a rotating group of film-industry executives, including representatives of studios, theater owners and the MPAA itself. Names of members who hear appeals are not made public. At least nine panelists must convene for an appeal, and a two-thirds vote is required to change a rating.

David Dinerstein, whose LD Distribution is to release director William Friedkin's crime drama "Killer Joe" this year, appealed the film's NC-17 rating, which the MPAA said it awarded for "graphic aberrant content involving violence and sexuality, and a scene of brutality." He argued that several other recent films were as explicit. But the board affirmed the adults-only rating.

"We feel strongly that 'Killer Joe' was arbitrarily and unfairly rated NC-17," said Dinerstein, who has yet to decide what his next steps will be. "Other films, including 'The Girl With the Dragon Tattoo,' 'Black Swan,' 'A History of Violence' and 'Pulp Fiction,'?contain comparable adult material and received the less restrictive R rating, as well as 'The Hunger Games,' which features kids killing their peers and is rated PG-13."

Independent filmmakers have long believed that the appeals board can be biased in favor of movies from the six large studios that are members of the trade group. Still, the only appeal for a 2012 film from an MPAA member, 20th Century Fox's R-rated "This Means War," did not succeed. Besides "Haywire," "Bully," "Killer Joe," "Sea Level" and "Perks," the group also heard appeals on "Apart" and "The Possession."

All of the media coverage surrounding appeals such as the one for "Bully" may have also shown filmmakers that appealing — while not certain to yield a new rating — is worth a shot.

"Maybe it's just that there's more familiarity with the process," said Alan Friedman, a lawyer who has been involved in several recent appeals. "Whether it's easier or harder to prevail, I don't know for sure. But the decisions themselves are getting more publicity."