I don't know why this is standard practice in the US but it rubbed me the wrong way. LE should be taking the lead on this.
Also this NYT story: https://www.nytimes.com/interactive/2019/09/28/us/child-sex-...
IWF is the British hotline.
They exchange information with each other and pass information through to law enforcement after reviewing it.
Different hotlines may differ in what reports they're willing to take depending on what's banned locally. IWF is legally mandated to take reports on cartoons. NCMEC isn't in theory but they might take it and pass it onto the user's country due to lack of manpower.
As a comparison, CERT operate the same model: informing them of an attack can lead to them becoming bound into LEA activity which requires them not to disclose.
IWF was set up to allow ISPs to find and remove that content without being criminalised for taking action on it, and then to safe-guard the children who were in those images and videos.
Expansion into computer-generated imagery follows from changes in UK law that made computer generated images of child sexual exploitation, (and also images involving sex with corpses, realistic depictions of rape, and realistic depictions of acts that harm genitals) illegal.
> In 1996 the Metropolitan Police notified the Internet Service Providers Association (ISPA) that some newsgroup content being carried by UK internet service providers (ISPs) were indecent images of children. The police believed this may have constituted a publication offence under the Protection of Children Act 1978 (England and Wales) by the ISPs. Efforts were then made to find a way to combat the hosting of such content in the UK whilst protecting the internet industry from being held criminally liable for providing access to the content.
> Following discussions between the former Department of Trade and Industry (DTI), the Home Office, the Metropolitan Police, some ISPs and the Safety Net Foundation (formed by the Dawe Charitable Trust) an R3 Safety Net Agreement regarding rating, reporting and responsibility was created by ISPA, the London Internet Exchange (LINX) and the Safety Net Foundation. A key outcome of the Agreement was the formation of the Internet Watch Foundation (IWF).
> The IWF was established to fulfil an independent role in receiving, assessing and tracing public complaints about child sexual abuse content on the internet and to support the development of website rating systems. Since we were set up in 1996 we have been operating a Hotline service for the public to report potentially criminal content and we have been issuing ‘takedown notices’ to UK ISPs in partnership with the police so they can remove the content.
> The Hotline was formally launched in December 1996 to combat child sexual abuse images and criminally obscene adult content hosted in the UK. Since then we have been continually improving our practices and developing unique services for the internet industry to help them make their services safer for their users.