Wired on Friday: It's a little shocking to see internet censorship so close to home: Turkey, so assiduous in wooing its fellow countries in an attempt to join European Union, this month decided that some videos on YouTube were too sensitive for its citizens' eyes.

An Istanbul court, shown a copy of a YouTube video, ordered Turk Telekom, the privatised national internet service provider (ISP), to remove it. Turk Telekom obliged by blocking the entire site from its customers, redirecting them to a page that explained the censorship.

The videos in question touched a sore spot in the Turkish national psyche: they were scurrilous attacks on the country's founder, Ataturk, devised and deployed by some Greeks to get a rise out of their neighbours. But blocking the entire site was a sledgehammer approach.

Following complaints from Turkish internet users, the court begrudgingly dropped the ban a few days later. But Istanbul's actions to block an entire site was still enough to prompt the question: is Turkey an open enough country to join the EU?

As it happens, there's a little self-censorship being practised here by our European allies. A number of countries in the EU practise internet censorship, either at the behest of government, or in a business-led initiative by ISPs to block certain websites.

In Germany and France, search engines like Yahoo! and Google regularly block Nazi and other hate speech at the request of the government. Google attempts to mark the demise of the links, by noting that items have been removed. The list itself is private, with no legislative or judicial oversight. There is little due process that describes how a site joins the list, and none that I have found to get oneself off it again.

In the UK, a private organisation does the blocking. The Internet Watch Foundation (IWF) acts as a helpline for net users reporting illegal content (primarily child pornography). A service run by British Telecom, Cleanfeed, takes the list of allegedly illegal Urls from the IWF, and prevents access to them for its customers.

Other ISPs also use the service, as do 3G mobile telephone services. The service is not supervised by the government, although the British home office has set a target that all ISPs offering broadband internet should have blocking systems in place by the end of 2007.

Blocking child pornography or Nazi imagery does not sound that bad an initiative, either from the public or the private sector. But both of these systems create the instruments of narrowly-targeted, near invisible, nationwide instruments of censorship, to a degree the Turkish courts could only begin to imagine.

The subtlety of the system compared to the blanket ban on Turkey is worth noting. With Cleanfeed, it is possible to ban individual webpages, and even individual images or movies.

With a system like this in place, the individual censorship of particular items would be almost invisible. Even visitors to the banned material could be palmed off with a fake "error page".

The Turkish government could have pinpointed a single Ataturk video, leaving the rest of YouTube untouched. Barely a murmur of protest might be heard.

Errors, of course, are made. Last year, the IWF removed from Google, and may have blocked from British Telecom's broadband users, key parts of the popular discussion site, 4chan. While 4chan is not exactly CNN (its visitors specialise in exchanging and remixing funny, often deliberately shocking images), neither is it a paedophilia website.

The fact that such a popular site was blocked from search engines for over six months in Britain is profoundly disturbing.

Without proper government oversight, these blockings could easily sprawl out from clearly illegal content to other, more controversial censorship.

Authorities at the highest level in Britain and the EU have already made it clear that they are interested in blocking material that "glorifies terrorism". Will that extend to political censorship? Will the Animal Liberation Front vanish from the net? Will Sinn Féin?

Censorship of content is a decision that each country makes for itself, but while the European Declaration of Human Rights makes some exemption for limiting free expression, the least we can ask as free citizens is that the process of making content disappear from the internet has some public exposure.

After all, even those who would ban books would allow a banned book list to be published.

And, talking of a history of banned books, what of Ireland itself? Goodness knows that the State goes through its own paroxysms of censorship both of the press and film world, but Ireland does seem to keep its internet connections relatively untouched.

I suspect that is not so much because of our more enlightened view, but because it has not yet occurred to the more prudish parts of the establishment that such censorship is possible.

When they finally turn their shocked eyes to the net, they will at least be able to borrow and buy subtler technology than Turkey possesses.

With the invisible removals of Britain, combined with the unrecorded blacklists of Germany, will we even notice when the internet censor begins to create his little bookmark list? Or even if such a functionary exists today?

Danny O'Brien is international outreach co-ordinator of the Electronic Frontier Foundation.