Not knowing anything about it but I suppose various governmental agencies maintain corpora of nasty stuff and that you can say to them - hey we want to roll out anti-nasty stuff functionality in our service therefore we need access to corpora to test at which point there is probably a pretty involved process that requires governmental access also to make sure things work and are not misused otherwise -

how does anyone ever actually fight the nasty stuff? This problem structure of how do I catch examples of A if examples of A are illegal must apply in many places and ways.