The Federal Government plans to undertake a technical review of its Refused Classification (RC) Content blacklist if and when it reaches 10,000 web addresses.
In an official response to parliamentary questions on notice yesterday, Communications Minister Stephen Conroy said ISP-level filtering of 10,000 URLs would have no discernable impact on network speeds.
He addressed suggestions noted in Enex TestLabs's 2009 Content Filtering Trial Report that 10,000 URLs may be a tipping point for load/performance degradation. At the time of the Enex study, the blacklist contained little over 1,000 URLs.
"The Government will monitor the number of URLs contained on the Refused Classification Content list and liaise with ISPs if the list begins to approach 10,000," Conroy said.
"If the list approaches 10,000 URLs, the Government will undertake a technical review of filtering a larger list of URLs."
The RC Content blacklist is expected to include Australian Communications and Media Authority's (ACMA) blacklist as well as URLs from overseas agencies.
Because the filter was intended to block only specific URLs and not entire domains, Conroy said, each item to be blocked would need to be listed specifically.
According to Electronic Frontiers Australia chair Colin Jacobs, there was a "significant risk" that the 10,000 milestone would be reached very quickly.
"If a website contained 10,000 images, each at a separate URL, how would this be handled by ACMA?" he wrote on an EFA blog.
"Or if somebody renamed a legal but RC image 10,000 times and uploaded them to a web server, and complained about all 10,000 URLs?
"Any such expensive and massive system needs to be more robust from the beginning," he said.
Conroy also revealed plans to develop new systems to manage, monitor and review items on the blacklist.
Currently, ACMA's blacklist is manually managed, and reviewed each quarter to determine if any URLs should be removed from the list. A replacement list is sent to filter software vendors after each review.
While Conroy did not reveal the cost of the review, each item of online content that was referred to ACMA cost the agency between $173 and $685 to investigate and classify last year.
Conroy considered the current manual review process appropriate for current, voluntary filtering arrangements. However, this was likely to change as RC Content list was established.
"There is no automated monitoring of URLs on the list currently maintained by [ACMA] and provided to filter software vendors," he said.
"[ACMA] intends to develop systems to manage the Refused Classification Content list once the regulatory framework for the list is in place and will consider the requirement for monitoring the list as part of this process."