How movies are assigned their ratings has become something of a hot topic in the past few years. Although I have never seen much written about the subject, listening to the commentaries on several DVD’s (Kevin Smith’s in particular) have offered some insight into how the MPAA rates films. There is of course the documentary This Film Has Not Yet Been Rated which I could watch about twenty minutes of before becoming bored with the director and his need to be in front of the camera.
This article pertains to the rating system in Ontario. What is of interest is how forthcoming their ratings board is and how well defined their categories are for determining the ratings of their films. This is a link to their site – http://www.citytv.com/toronto/citynews/entertainment/movies/article/75111–how-a-movie-is-rated-in-ontario
On this note there is another ratings group, independent of any government as far as I can tell, called Common Sense Media. I find this site and the ratings they have posted on Netflix to be very helpful. They offer detailed explanations for each film so that the reader can understand why this film is deemed 16+ and how it differs from another film with the same rating.