Internet Filtering Myths

Why is Tech Liberty opposed to an Internet filter that is claimed to block access to child pornography?

We have been asked this question from time to time, with the unspoken implication that by opposing the filter we are unwilling for something to be done about it, or that we are monsters who support such material. We do not support the production or distribution of such material. While we believe that free speech is an important value that should not be lightly overridden, we also accept the right of societies to choose to censor.

The production and distribution of child pornography are serious crimes that should be eradicated but that does not mean that any solution should be immediately deployed without question. In this post we attempt to debunk some of the popular myths about Internet filtering.

Myth: The filter will reduce production of child pornography

Filtering the Internet, even perfect filtering of the Internet, will not stop people abusing children. The Department of Internal Affairs, who are implementing the filter, admit this in their Code of Practice:

In particular website filtering is effective only after the fact and does not prevent the creation of illegal material nor, in the case of images of child sexual abuse, the exploitation of children. (Source)

Myth: The filter will remain limited to child pornography

The Department of Internal Affairs have cited “public pressure” as a reason to implement Internet filtering to block child pornography. They have also promised that the scope of the filter will not be expanded

However, every group with a barrow to push will be attempting to get certain sorts of material blocked. The Scientologists have already asked the Australian government to block sites that promote “religious vilification”, and locally Family First have asked the government to greatly expand the filter. There have been calls to block sites on suicide, to prevent children taking their own lives.

Sadly, we believe that public pressure will lead the government to block more and more material in the desire “to be seen to do something”, even if that something is ineffective.

Myth: The filter is just enforcing our existing censorship regime

Decisions to filter other forms of content – books, movies, newspapers, magazines, television, video games – are published by the Chief Censor. This allows the public to know what is being banned so that they can check that the censor is not going beyond the legal bounds of what can be censored.

The decisions about what to block via the Internet filter will not be public – no-one outside of the Department or its advisory groups will be allowed to know what is being filtered and why. If you do find a censored site and appeal the block, the Department has deliberately designed the system so that they will have no way of contacting you to justify their decision.

The Internet filter is a step away from our current open regime towards a secret censorship system.

Myth: The filter is optional

The filter being implemented is not optional. Even if your ISP choses not to participate in the scheme, you have no assurances that their connections to other ISPs will also not be filtered. There are a limited number of network paths out of New Zealand – and if all of them are filtered, you and your ISP’s choices are irrelevant.

Myth: The filter will not affect the stability or security of the Internet

The filter injects data into the equipment ISPs use to carry your traffic that diverts it. This data can leak and have a catastrophic effect on the Internet. In 2008, Pakistan injected into local ISPs a block to the popular video sharing site YouTube. However, rather than just blocking local Pakistan users from YouTube, the block spread to ISPs all over the world. The DIA filter will use similar methods to insert its blocks, and has the same potential to cause outages all over the world.

Worse still, the DIA system is designed in a way that it can be poisoned to block any website. In order to maintain the list of blocks, the DIA systems will periodically ask for updates on where websites are hosted. Since blocked websites have control over that information, they can manipulate the addresses the DIA will inject, causing the DIAs filter to collapse under unexpected load, while crippling legal access to sites.

The Australian filtering system drops as much as 3% of legitimate connections. It doesn’t sound like a lot, but every web page is made up of tens or hundreds of connections. There won’t be a problem with an occasional page, rather it will be parts of pages failing to load and bugs in online applications, all the time. The DIA has not published any data on the drop rate of legitimate connections.

Myth: The filter works 100% of the time

The filter can only block what it knows about. Claims that the filter is 100% effective are moot, it could not be anything other than 100% effective if the criteria is ‘stuff we know about’.  The Department cannot put a finger on the actual effectiveness of the filter because they don’t know about what they aren’t blocking.

Secondly, it is trivial for any motivated person to work around the filter. This can be done by using an account on an overseas machine, or any of the software and systems that have been designed to help people in places like China and Iran to work around their government’s Internet censorship.

Myth: The filter will protect you from accidental viewing

One claim also made is that the filter will protect people from accidentally seeing offensive material. But how often does this actually happen? We know of no cases where someone has accidentally stumbled across child pornography on the web.

If people are concerned about them, their employees or their family stumbling upon unsavoury images on the internet, many ISPs offer a much more comprehensive filtering system or it is also possible to buy blocking software to install on your computer.


While implementing any solution may make people feel good about “doing something”, efforts are better spent on something that will actually result in an outcome. For example, we support the Department of Internal Affairs in the work they do to infiltrate and arrest groups of people who trade in objectionable material.

TechLiberty is opposed to the Internet filter because it does not work, it interferes with legal usage, it does nothing that the public has been told it will do, and it does not prevent a single instance of abuse of children taking place.