The problem with such a plan is multi-layered: First, there is no transparency in the selection of URLs to be blacklisted, and no accountability from the regulatory bodies creating the blacklists. The �reputable international organizations� providing child abuse URLs have not been named, but may include the Internet Watch Foundation, a UK-based organization that in 2008 advised UK ISPs to block a Wikipedia page containing an album cover from the 1970s that they deemed might be illegal.

The ACMA itself has run into problems with its blacklist as well. After Wikileaks published the regulator�s blacklist in 2009, it was discovered that the list contained the website of a Queensland-based dentist, as well as numerous other sites unrelated to child sexual abuse or illegal pornography.

Second, filtering does little to curb the trade of child pornography, much of which is traded across peer to peer networks and VPNs. Filtering it from the world wide web may simply push it further underground.

Third, there appears to be no appeals process in the Australian ISPs� scheme, thereby making it difficult for sites erroneously caught up in the filter to challenge the block.

Lastly, the introduction of a filter sets precedent for the ISPs to filter more sites in the future at the behest of the ACMA. If the ACMA were to make the decision that sites deemed "indecent" or politically controversial--for example--should be off-limits, would the ISPs comply?