It appears that Anne P. Mitchell, Esq. via NANOG <nanog@lists.nanog.org> said:
I'm part of a postgraduate team at Dublin City University working with Chirp, a startup developing real-time, embedded child-protection software for telecom operators.
The moment you put the point of child protection on the telco you open the telco up to all sorts of liability lawsuits. A stunningly bad idea.
I take your point, but he's in the EU, not the US, and I wouldn't be surprised if EU regulators expected their telcos to do something about CSAM sent as messages to or from their phones. There are technical issues, too, like how reliable the fingerprinting is and what the consequences of false positives and negatives are, but they're different from the legal issues. R's, John