Hirsch charts bullying and its dire impact on five families. In one story, a family attempts to initiate a community discussion on bullying when their 17-year-old is found dead at home after being bullied at school.
Another thread involves a father who becomes an anti-bullying activist after his 11-year-old son is found dead.
"In the last couple of days we had heard that Tyler had his head shoved into a wall locker," recounts his father.
"They said he's a geek. Some kids had told him that he's worthless, to go hang himself. And I think he got to the point where enough was enough." Other pupils recount how they are punched, strangled, sat upon and taunted.
The Weinsteins contend the "R" rating would prevent Hirsch from communicating "America's bullying crisis" - the film's website says 13 million American kids will be bullied in the US this year - to those who need to be reached most of all; the victims and perpetrators.
This would effectively stop the film being used by schools and communities in education campaigns to address bullying.
Harvey Weinstein, whose personal appeal last month failed to shift the MPAA, said plans to bus 40,000 pupils in the Cincinnati School District to see Bully in cinemas would have to be cancelled because of its "R" rating.
The MPAA and NATO insist the rating is necessary because the word "f***" is uttered six times on the soundtrack.
Yet one scene in The King's Speech, a Weinstein produced film that won Best Picture last year, featured five utterances of "f***". The soundtrack was muted so this word was only heard twice and the film was given a PG-13 rating.
Such inconsistencies suggest a dysfunctional ratings code.
"The film shows students being bullied," says Hirsch, who believes stories he has heard of bullying in New Zealand suggest a "very similar landscape" to the US. "And it's not pretty. They use this language. It's important these experiences aren't marginalised. That the film gives voice to experiences for people who go through bullying day in, day out. It's not just 'kids being kids' or a 'rite of passage'. It's important the movie stands uncensored."
The Weinsteins have threatened to boycott the MPAA rating process, in which the movie industry voluntarily polices itself, rather than risk US or state censorship.
In response, NATO warned it might slap an NC-17 certificate - allowing no one under 17 into cinemas - on all Weinstein films.
In a letter to the Weinsteins, NATO's president, John Fithian, said that while he was "personally grateful" as a father of a 9-year-old that the film had addressed bullying, Bully was not exempt from the industry's rules.
"Were the MPAA and NATO to waive the ratings rules whenever we believed that a particular movie had merit, or was somehow more important than other movies, we would no longer be neutral parties applying consistent standards, but rather censors of content based on personal mores."
The Weinsteins countered that this stance was "completely unconscionable, not to mention unreasonable". They said Bully addresses a vital contemporary issue, citing last month's high-school shooting in Cleveland where 17-year-old T.J. Lane killed three students, the latest incident where student killers are said to have been relentlessly bullied.
The dispute has now gone viral. Katy Butler, a Michigan high school student who says she was bullied because she is a lesbian, believes Bully "could save thousands of lives".
Her online petition - "Stomp out bullying and cyber bullying" - on Charge.org aims to deliver one million signatures to President Barack Obama and Congress by June 1.
"I'm speaking out for all those students who suffer every day because of bullying," Butler said. "The MPAA needs to give Bully a PG-13 rating [some material may be unsuitable for children under 13] so the students being bullied, and the bullies themselves, can see this film and schools can show it as well."
As of March 6, the petition had gathered 223,915 signatures.
"This is exactly the kind of conversation we wanted to have," says Hirsch, who was "blown away" by the petition and met Butler not long before we spoke.
"There's a lot of pain around this issue.
"And young people have not had an opportunity to express this. They are saying this is a movie for us."
One unexpected result of the ratings impasse is it has sparked online conversation about bullying.
In 2001, a US National Institutes of Health (NIH) survey of 15,686 school pupils found bullying was "widespread in American schools, with more than 16 per cent of US school children saying they had been bullied by other students during the current term".
Love Our Children USA, an advocacy group, claims three million children are bullied each year, but says the epidemic is under-reported and the real number is threefold. The group says 3.3 million bullying allegations involving six million kids were reported in 2009, while up to 160,000 pupils skip school each day to avoid bullies.
"People who were bullied as children are more likely to suffer from depression and low self-esteem well into adulthood, and the bullies themselves are more likely to engage in criminal behaviour later in life," noted the NIH.
A study released last month by the American Journal of Preventative Medicine confirmed past research that showed gay, lesbian, bisexual and transgender children were more likely to be bullied, and to kill themselves as a result.
Traditionally, schoolyard bullying involves verbal taunts, ostracism or physical violence. Social media has amplified this threat, as the Charge.org petition indicates.
A 2010 NIH study found victims of "cyber bullying" are at "greater risk of depression" than "bully-victims" who are bullied and who go on to bully others. Unlike face-to-face encounters, cyber victims are often unable to identify their harasser. They are "more likely to feel isolated, dehumanised or helpless at the time of the attack".
The New Zealand Law Commission is canvassing public opinion on how to curb cyber bullying without harming free speech.
However, as the Change.org petition shows, online activity can also be a community forum for combating bullying.
While Facebook and other social sites can facilitate bullying, Jessica Klein, assistant professor of Sociology and Criminal Justice at New York's Adelphi University, argues in The Bully Society: shootings and the crisis of bullying in America's schools, published this week, that right-wing economic policies also play a role.
Klein argues the Reagan-era push to deregulate capitalism and stress profit at all costs fuels social isolation and equates respect with aggression. It is a "bully economy" that has spawned hyper-masculinity, asserted by boys and learned by girls. One result, Klein suggests, is the upward trajectory of school shootings: from 27 between 1979 and 1988, to 55 between 1989 to 1998, and 66 between 1999 and 2008. Between 2008 and 2011, there have been 43 shootings.
Eric Harris, who helped kill 12 students at Columbine High School in 1999, wrote "your children who have ridiculed me, who have chosen not to accept me, who have treated me like I am not worth their time" in a note.
"School shootings are just one symptom of a culture of despair on our schools," Klein told CNN after the Cleveland killings.
"Many students are depressed. Many are anxious. Many are truant. A lot turn to substance abuse. A lot cut themselves.
"We see a lot of suicides. When you talk to students across the country about what bothers them, they say pretty much the same thing as many of the kids who commit school shootings. They talk about being called gay. Girls talk about being called sluts ..."
It is a cruel litany familiar to bullying victims. One solution, says Klein, is for schools to foster a "culture of acceptance", rehabilitating compassion as a social more.
