2.1. British Board of Film Classification

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In the UK the British Board of Film Classification (BBFC) rates both motion pictures and videos (and an increasing number of video games). The rating system was introduced in 1913 and, as of 1985, also rates videos. County authorities are ultimately responsible for film ratings for cinema showings in their area. County Councils often ignore the BBFC advised rating and rate films with another BBFC certificate in their county only. Rating certificates from the BBFC are not legally binding whereas those for videos are. British cinemas generally stick closely to the policy of ratings and a young person may often be asked for proof of age if deemed younger than the rating.

The current BBFC system is:

• Uc (Universal Children) Suitable for all, but especially for children under 4. Used for video only. Retired in 2009.
• U (Universal) Suitable for all. (The board states that while they cannot predict what might upset a particular child, a 'U' film should be suitable for audiences aged 4 and older).
• PG (Parental Guidance) General viewing but some scenes may be unsuitable for young children. (It is the board's policy that movies rated 'PG' should not disturb a child of about 8 years of age or older; however, parents are advised to consider whether the content may upset young or more sensitive children).
• 12A (12 Accompanied/Advisory) Recommended for 12 years and older. People under 12 years must be accompanied by an adult. (Exclusively for cinema, '12A' was first implemented on The Bourne Identity and, contrary to popular belief, not on Spider-Man, which was first released months before, under the previously fully restrictive 12 certificate, and then immediately re-released to take advantage of the new guidelines).
• 12 Recommended for 12 years and older. Anybody under 12 may see it, as long as parents of guardians say they can. Nobody younger than 12 may rent or buy a '12' rated video. (Until 31 August 2002, this mandatory certificate used to apply to cinema exhibitions as well).
• 15 Suitable only for 15 years and older. Nobody younger than 15 may see a '15' film in a cinema. Nobody younger than 15 may rent or buy a '15' rated video (these films may contain offensive or emotionally harrowing scenes or strong language and violence).
• 18 Suitable only for adults. Nobody younger than 18 may see an '18' film in a cinema. Nobody younger than 18 may rent or buy an '18' rated video (These films may contain extreme gore/violence and/or sexually explicit content).
• R18 (Restricted 18) To be shown only in specially licensed cinemas, or supplied only in licensed sex shops, and to adults that are older than 18 years old. (These films contain sexually explicit, pornographic content.)

Here you have a thorough Comparison between the film rating systems in different countries. And here is an article in The Guardian about the work of the BBFC and a selection of films censored in the UK.