Okay, so the ISPs are to blame for the IP address problem rather than the IWF. But that doesn't change the point that something has gone wrong here.
Comparing Wikipedia's blocking of people editing Wikipedia to this censorship is laughable. There's a difference between controlling who can access *your own site*, and trying to censor other sites!
"Web hosts must not wait for an image to be declared unlawful by a court when they receive a complaint, albeit only a court can declare an image unlawful. If they wait, there is every chance that the declaration will come at their own trial."
And that is Wikimedia's choice to make. And since they are in the US, it is up to the US authorities to notify them.
"Yet that is no defence. Amazon should get rid of it too, or, at the very least, block the image from UK visitors."
That's not the point. The question is, is the IWF going to block them too?
"The IWF says that its system cannot ban individual JPEG files, though. It says that its system is designed to be simple, because that is what the ISPs want. So it bans pages on which images appear, not the images themselves. That is not an over-reaction, in my view."
Censoring *text* is an over-reaction, in my view, the paying customer. If the IWF's system can't handle blocking images, then that's rather mad considering that the system was supposedly designed for blocking images! This system also means that the image is still available, if you know the URL of the image directly. So on the one hand it blocks legal text, yet it turns out it's no good at blocking child porn images anyway!
"Yes, that is a form of censorship; but not all censorship is evil. Wikimedia should know that."
A straw man argument - no one is claiming that censoring actual child porn images is wrong. Wikimedia do know that.
As for the idea that ISPs can choose to block what they like - well sure, but (a) their customers damn well have a right to complain and raise awareness about such actions, and (b) you can damn well be sure that any site which is blocked will also complain, and consider legal action.
There is also the wider issue of fears that ISPs have signed up to the blacklist, out of fears that the Government will force them to do so if they do not.
Whoever is to blame - the ISPs, the IWF or the Government - both individuals and Wikimedia are right to kick up a fuss about it.