URL List Policy

IWF's core function is to provide an internet Hotline for the public to report their accidental exposure to criminal online content within our remit and as the national 'notice and takedown' body for that content so it is quickly removed from circulation. We consider removal at source to be the most effective way of combating child sexual abuse images online and other criminal content within our remit which has been almost eradicated from UK networks.

We also work internationally to remove child sexual abuse images from the internet by passing details of every identified non-UK website to our partner hotline in that country so they can investigate it within their own legislation and in cooperation with their national law enforcement agencies. In the absence of the existence of an in-country hotline, IWF notices are sent to the UK National Crime Agency.

Whilst steps to have content removed are in progress, the UK internet industry has voluntarily agreed to block access to them using a list provided by the IWF. We consider blocking to be a short-term disruption tactic which can help protect internet users from stumbling across these images, whilst processes to have them removed are instigated.

Further information

On 7 November 2002, the IWF Board noted the legal advice which enabled the release of the child sexual abuse content URL list to IWF members for the purpose of implementing blocking or filtering solutions to protect their customers from being inadvertently exposed to abusive images of children. During board meetings in late 2004 and 2005, the IWF Board agreed the principles and procedures under which the child sexual abuse content URL list would be made available to members and under licence to specific non-members. 

Since 2004 many companies have chosen to make use of this list to protect their customers, namely, internet service providers, mobile operators, search providers, and filtering companies. National and international law enforcement agencies and INHOPE Hotlines may also access the list on a mutual exchange basis for non-commercial use.

Every URL on the list depicts indecent images of children, advertisements for or links to such content. The list typically contains 5,000 URLs but is subject to fluctuation. The list is updated twice a day to ensure all entries are live. As well as making the internet a safer place for everyone, this initiative can help to diminish the re-victimisation of children by restricting opportunities to view their sexual abuse and may disrupt the accessibility and supply of images to those who seek them out.

Unfortunately, blocking cannot put an end to offenders abusing children nor can it effectively deny determined criminals who are actively seeking such material.

Our systems and processes in compiling this list are periodically inspected and audited by eminent independent experts. The URLs are assessed according to UK law, a process reinforced by reciprocal police training with each image being categorised in line with criteria set out by the UK Sentencing Council.

IWF’s role in this blocking initiative is restricted to the compilation and provision of a list: the blocking solution is entirely a matter for the company deploying the list. Our list is designed and provided for blocking specific URLs only. Any decision to convert or adapt the list to block whole domains may lead to the over blocking of legitimate content and is not supported by the IWF.

Blocking facilitated by the use of our list applies only to potentially criminal URLs related to child sexual abuse content on publicly available websites. The distribution of these images through other channels such as peer-to-peer is a matter for our police partners. IWF has no plans to extend the type of content included on the CSAM list.

Notifying the website owner and or host of any blocked URL is the responsibility of a Hotline or relevant law enforcement agency in the country believed to be hosting the content. However any party with a legitimate association (*1)  with the content or a potential victim or the victim’s representative, hosting company, publisher or internet consumer who believes they are being prevented from accessing legal content may appeal against the accuracy of an assessment.

(*1) A party affected by the issue of a notice or blocked by the addition of a URL to the IWF URL List.

Frequently asked questions (FAQs)

We have a responsibility to provide detailed information about our facilitation of the blocking initiative therefore we hope these FAQs can address any questions regarding our role in the process.

IWF URL List Policy and Procedures

The policy and procedures which are adhered to regarding the assessment and listing of child sexual abuse URLs can be found here (PDF 187KB).

Blocking Good Practice

Whilst the IWF facilitates this blocking initiative through the provision of a URL list and does not stipulate which blocking method is used, we do provide good practice guidance regarding the way in which blocking is conducted. These good practice recommendations for blocking are designed to maintain the principle of transparency and minimise over-blocking and latency issues.

Self Certification

IWF run a voluntary URL blocking self certification process which enables a member to test their blocking system to ensure that as far as they can reasonably ascertain, it is operating correctly from an end user perspective. For more information on this process please contact the Development Team.