In the 46 years that the ASA has been regulating advertising in the UK they have managed to successfully outlaw campaigns for containing either inaccurate, harmful or offensive material. This week the ASA ruled that the recent run of television commercials for Oasis Fruit Juice fell foul of these expectations.

The advert shows a young pregnant girl arguing with her mother before running away with her misunderstood 'cactus' boyfriend. Speeding off with the 'Cactus Kid', a man with green and spiky skin, the advert tries to mimic the feel of an American road movie and concludes with the line "Oasis - for people who don't like water."

After receiving 32 viewer complaints that the commercials condoned teenage pregnancy and under-age sex, the ASA conducted a formal enquiry. This week they decided to pull the adverts and concluded that the content was "offensive" and "irresponsible". A spokesperson from the ASA told the BBC that when they reviewed the characterisation of 'Cactus Girl': "We considered that the combination of her youthful appearance and the reference to her pregnancy meant [the advert] could be interpreted to condone under-age sex and teenage pregnancy."

With that assertion, the adverts now must not be broadcast again unless their content is sufficiently altered.

The latest in a long line of banned commercials, the ASA first started vetting campaigns in 1962. There have been some fairly high-profile cases in that time. In 1994 for example, ASA were forced to incorporate new rules for slimming products after JEM Marketing ran a campaign centred around an inhaler that claimed to subdue appetite. Coming in either chocolate, peppermint or grapefruit flavour, the advertising literature for "SLIMist" spray was heavily attacked by the ASA for its brandishing of unsubstantiated claims.

Other famous campaigns have been pulled for causing what is deemed 'serious or widespread offence'. This can include sexual or sexist imagery, obscenity or inclusion of highly sensitive material. For example, the second most complained-about commercial ever handled by the ASA is the legendary image of Sophie Dal for the YSL 'Opium' fragrance campaign. Completely naked and lying in a sexually provocative position, Dahl's skin is bleached a glowing white, her hair and lips are streaks of vibrant red and her closed eyes are painted a haunting green. Bringing such vivid images of sex and death so powerfully together proved too much for the UK censors and the image was pulled from posters and magazines in Britain.

The most complained about advert ever handled by the ASA however, was certainly not sexually provocative. Designed by the British Safety Council in 1995, the advert headed 'The Eleventh Commandment' features a black and white image of the late Pope John Paul II in a hard-hat and the slogan: "Thou shalt always wear a condom."

It may be hardly surprising that such irreverent treatment of such sensitive material caused the outcome it did. However, with the expanding networks of the media and advertising caused by the popularity of the internet, policing commercials is getting progressively more difficult. In light of this, some companies seem to have been trying harder to censor their own output. For example, so frightened by an influx of complaints about their "New York Deli Man" advert, which featured a kiss between two men, Heinz decided to pull the programme from broadcast so as not to incur a backlash from Ofcom or their core, family-centric, audience. Since Heinz took this decision however, the video of the advert has been seen thousands of times on the web.

With such publishing freedom on the internet, even banned or censored adverts can be found quickly and easily. The result, of course, is that sensitive material is getting harder and harder to censor and though the ASA have regulated advertising for over 46 years, they will need to seriously adapt and expand their operations if they are to continue to do so successfully for the next 46 years.