Aim a loaded gun at another human being on screen with the intent to cause pain and the film can get a PG-13 rating in the US.

Show full-frontal nudity on screen and the filmmaker can expect an R rating.

Or, your ‘art’ might get stamped RC - Refused Classification. That means no one can legally see it except the censors.

The disparity of the movie classification system in the US and Australia has long had its critics for being way too hard on consensual, even loving, sexuality on screen and way too easy on murderous violence.

A recent study released in a recent issue of Pediatrics reveals gun violence specifically in PG-13 films had tripled since the classification was introduced in the US in 1985.

Researchers contributing to the study examined 900+ popular PG-13 movies that had scenes with hand held guns where the intent was to harm or kill another living being – without being cautionary in tone.

For example, Skyfall received a PG-13 rating in the US. It was the second highest grossing movie of 2012 worldwide.

Other films that got a surprise PG-13 rating include The Italian Job and Cellular. Even the film’s poster featured Jason Statham aiming a hand gun.

All of these films got an M classification in Australia.

When I was a Trained Content Assessor by the Office of Film and Literature Classification, the trickiest area to make a decision was between a PG and M rating. This was an important distinction for parents of teens.

As a general rule of thumb, guns scenes in PG content were required to be non-realistic and non-persistent, show minimal blood, and the weapon and the person it was aimed at were not to appear in the same frame.

Back in the 80s, gun violence in a PG-13 film averaged about five minutes of screen time. Now, there is an average of fifteen minutes.

So how does gun violence unofficially increase in a movie classification system that’s been in effect for nearly thirty years? Are societal attitudes changing? Is it possible to lobby a classification body to get a coveted PG-13 rating so more bums can legally pay to be on box office seats?

A bit of clever editing can ‘soften’ the violence allowing a filmmaker to meet a classification’s criteria.

Even Tarantino had to make some artistic choices for his Kill Bill films so they could be legally released. One way to avoid deleting scenes with massive blood sprays is to remove the colour and make the sequence black and white. When all else fails, animate it.

Cartoons have the bizarre reputation of being less graphically violent than live action. The irony is some of them are almost total violence from start to finish simply portrayed with graphics like the iconic Road Runner & Coyote cartoon show.

PG-13 is a predominantly teenage audience in the US – the same nation most famous for many devastating high school mass shootings.

The reason the classification system exists is to protect minors from exposure to content that could be disturbing or even scar them for life. Parents need to remember ‘PG’ means Parental Guidance and provide it.

The screen is not an electronic babysitter.

Renée Brack is a journalist, media producer and adventurer.