A few weeks ago, we noted the UK government was considering plans to bring in an opt-out form of censorship, in what would amount to a kind of porn license, and that such an approach runs the risk of blocking a far wider range of materials. Now the Open Rights Group (ORG) has released a report that shows the "child protection filters" on UK mobile Internet networks are already overblocking sites:

It shows how systems designed to help parents manage their childrens' access to the Internet can actually affect many more users than intended and block many more sites than they should. It reveals widespread overblocking, problems with transparency and difficulties correcting mistakes.

The report and an update show that sites affected are found in the realms of digital rights (La Quadrature du Net and the Tor Project), technology (GigaOM, London Ruby User Group and the start-up organization Coadec), lifestyle, community and politics.

As the ORG report highlights, this kind of overblocking does not augur well for any UK government attempts to widen filtering to include fixed-line access:

If they follow a similar blueprint of ISP level filtering as mobile operators, all the problems we have highlighted would be reproduced at a larger scale. For example, most fixed-line connections are shared by a number of people using a variety of devices. Implementing filtering in that situation would require a range of approaches from whitelisting for young children to censorship-free connections for adults.

What's rather depressing is that news that overblocking is already taking place is no surprise: it's simply inevitable when this kind of network-level approach is taken. It underlines again why filtering has to be implemented locally:

we hope that if the government does pursue such a policy it will be flexible, concentrate on users and devices rather than networks, allow the tools to be properly described as "parental controls" and above all avoid turning on blocking by default.

Despite the mounting evidence of overblocking on mobile networks, it's not clear if any of those sensible suggestions will be implemented when it comes to fixed-line access -- details of the proposed UK legislation have yet to be announced.

Follow me @glynmoody on Twitter or identi.ca, and on Google+