Of course, my business is internet filtering, but there's a significant difference between what we do and what the government is pushing ISPs to do:
The government's plan is a "one size fits all" solution that can just be blanket-applied to everyone's internet connection without any serious administration overhead. I'm afraid that's just not going to work - the problems they discuss are exactly the problems that we expect to see with this kind of system.
- No filtering is 100% reliable - you're always going to find that some stuff that should be blocked gets through and some stuff that should be allowed gets blocked. So any reasonable filtering system is going to need a way for you to tweak the filters when this happens.
- Applying the same filtering rules to everyone is nonsense - you don't want adults to be restricted in the same way as preschool kids, for example.
- You're *never* going to stop people intentionally getting to any content through a technological solution alone - filtering helps prevent people stumbling across certain content by accident, but its not going to stop someone from actually going looking for this stuff. You can go a fair way by auditing the internet connection regularly and then going and *talking* to people who are breaking the rules. This is exactly what we encourage our (school) customers to do, and arguably for families its a lot more healthy for parents to talk to their kids about this stuff than just demand technology to bring their kids up for them.
- It is difficult for web site owners to find out whether their site is being blocked, and with each ISP using a separate filtering system it is a nightmare for them to get their websites unblocked on each system individually. Of course this is also a problem with our products, but I tend to think much less so because the people who want to access a website often have much more ability to ask the network administrator to allow access. Convincing an ISP to adjust their filters is probably going to involve a lot of hoop jumping.
- The slippery slope argument is a concern - installing centrally controlled filtering, with no oversight, on every ISP is concerning for freedom - who gets to decide what should or shouldn't be filtered? The government has already said they will be pressuring ISPs to filter websites expressing "extreme views", and with no oversight it makes you wonder what the establishment might consider an "extreme view".
- Not directly related to the reliability of the filtering itself, but in order to opt-out, ISPs have to keep a list of people who have said "yes I want to look at porn please" - I'd say that's pretty sensitive information to expect them to guard. I'm certainly looking forward to the day when the news papers publish a "list of MPs who told their ISP they wanted to watch porn" :)
Also something that struck me about the newsnight video is that the clips they showed of debates in the Commons about porn filtering frequently centred around "porn is really popular so we must stamp it out!", which seems completely backwards - surely if a significant proportion of the population want something then the government shouldn't be trying to prevent them getting it? After all, the government is supposed to work in the public's interest.