Since last July programs such as Cyber Patrol, NetNanny and Cybersitter have sold thousands of copies. Some have distribution agreements with organisations such as BT and CompuServe. The makers boast that their products "includes a list of thousands of Web sites that are not suitable for children" and "allow parents to censor what their children access on the Internet".
So far, so good - except that many of the "banned" sites include British sources holding useful or entirely innocent information. And the morality underlying many of the bannings is very American, quite unlike that which a British parent might be expected to apply.
Among the British sites on the World Wide Web your child would be unable to access when using the programs are the Campaign for Real Ale (Camra), the Prison Lexicon (which provides information about penal reform), the computing department of Queen Mary and Westfield College, Imperial College, the University of Stirling, the Internet connection companies Demon and Zetnet, and Telephone Information Services - which offers weather and share reports but not sex lines.
Between them, the programs prevent access to tens of thousands of Net sites. Blocks are triggered by certain words - though it is impossible to find out what these are. They thus impose an American system of morals - on religion, weapons, drugs, alcohol and sex - to data which British children might be expected to know about, or could obtain from newspapers.
No operators of the above sites were aware that they were "blocked", and all were mystified by it. "Which self-selected Mary Whitehouse put us on their list?" asked Iain Lowe, research manager of Camra.
In Camra's case, the answer is a team of researchers at Microsystems Software in Massachusetts, which has been selling Cyber Patrol since 1995, and claims 80 per cent of a fast-growing market. "Camra's site is blocked under our code for beer, alcohol, wine and tobacco," said Dick Gorgens, chief executive. "It was added in June when it was advertising a beer festival."
Mr Lowe responded, "We don't promote under-age drinking. But pubs in this country are allowed to apply for children's certificates: all the family can go. And we have had inquiries to our site from GCSE students doing projects on the economics of the brewing industry."
Mr Gorgens denied the program was imposing American morals on British users. However, the panel that reviews the banning of sites includes no Britons, although it does include representatives from the National Rifle Association and the right-wing anti-pornography Morality in Media group.
Mr Gorgens said parents could allow access by their child to any site they wished. But the operation of the programs, which are meant to let children work without a parent's supervision, makes it impossible for a parent to know in advance what sites are blocked. The list of banned sites is kept in a coded list on the computer which cannot be reviewed.
"Banning" programs began appearing 12 months ago in reaction to fears about the prevalence of pornography on the Net. But they have come under attack for introducing censorship without explanation.
"A close look at the sites blocked by these programs shows they go far beyond just restricting 'pornography'," said Brock Meeks, an Internet journalist and consultant who, with fellow journalist Declan McCullough, obtained a decoded list of the sites banned by the programs earlier this month, and revealed their indiscriminate breadth in an Internet mailing list, Cyberwire Dispatch.
Steve Robinson-Grindey, who runs the Prison Lexicon site, said: "It is an electronic encyclopaedia of everything concerning penal affairs in England and Wales. It is extensively used by schools and universities. Even China allow access to the site." He thought it might be banned because "obviously they rely on search words for filtering - in which case they would discover the words sex, Aids, homosexual, and so on."
"We don't get too many complaints," said Marc Kanter, marketing director of CyberSitter, based in California. "This is a tool for parents, teachers and employers. If you have a site that has information about Aids, there will be a conflict. We do block anything geared to homosexual lifestyles."
This raises the question of how an American child could find out about US sporting heroes such as Magic Johnson, the (heterosexual) basketball player who is HIV-positive (reckoned to have contracted the virus through sexual contact), or Arthur Ashe (who died of Aids following a contaminated blood transfusion). And if HIV infection is permissible in EastEnders, why should it be banned on a computer?
"We don't advise people to use that sort of software," said Merlyn Kline, technical director of Zynet, whose zynet.co.uk domain - providing Internet connection to thousands of users - is blocked by one of the programs. "The company hasn't contacted us. But the sort of person using software like that doesn't understand what's going on. They tend to set it up and let the children use it.
"The key is to educate children, so that if they come across damaging material it won't damage them. And is that software going to stop them swapping copies of Playboy? Of course not. These programs give a false sense of security."
This is the crux of the argument: rather than teaching the clever human what to filter out, such programs leave it to the stupid computer. "But the computer can't make the judgement about what's wrong and what's right. People have to do that," said Mr Kline.Reuse content