Overblocking is not a new problem - over two years ago, Homeland Security took down 84,000 innocent sites at a stroke - so you might have thought that those employing this blunt instrument would take a little more care these days. However, things seem to be getting worse, not better. In Australia, the Australian Securities & Investments Commission (ASIC) has just scored a whopper:

The largest number of sites censored when attempting to block one particular site ASIC believed was defrauding Australians was 250,000. Of these, ASIC said about 1000, or 0.4 per cent, were active sites. It said the 249,000 other sites hosted "no substantive content" or offered their domain name up for sale, rather than hosting a fully-fledged active site.

I wonder how the ASIC established that 249,000 had "no substantive content". I can't believe it really checked all of them. And that's the big problem with overblocking: when huge numbers of sites get taken down by mistake, there's no way of telling what just fell off the Web, and what obscure but possibly important information is no longer available.

At least ASIC realizes that its current ham-fisted approach isn't acceptable:

ASIC told senate estimates in its opening statement that it was now examining how it could ensure only a site's specific domain name was blocked and ways it could alert the public to a site being blocked via a pop up page. It was also examining ways such a page could indicate why access was blocked and to whom queries could be made to dispute a block.

That's good, but maybe it would have been better if it had explored those options before shutting down nearly a quarter of a million innocuous sites by mistake.