So what happens if Facebook's system flags a message, it is reviewed by their staff and then dismissed as non-actionable, but turns out to be the precursor to a severe criminal act? Does the blame come back on Facebook for failing to prevent this crime?
Possibly failure to properly notify will result in some sort of legislative slap on the wrist, but not for failing to prevent it. That isn't their responsibility.
But didn't they make it their responsibility the minute they began screening messages with the intent of reporting crimes? Selective enforcement whether by choice or mistake isn't an option they can choose here.
And criminal legalities aside, I would be more concerned about the civil litigation from the victim or victim's family. Facebook pledged to prevent crime against its users, witnessed evidence that a crime would take place, and then failed to act. Tell me no one would go after Facebook's deep pockets in this situation given they could have reasonably prevented whatever crime took place, even if it meant reporting it to the proper authorities.
It may just be professional paranoia talking, but I can't see how this doesn't release them from some sort of liability in a worst-case scenario.
Yes, and since they claim that nearly 1 out of every 7 people on the planet (900 million users!) are on facebook, I'd take the default position that if any crimes happen they probably failed to report it. :)