provides a graphic example of the problem, although, in a sense, it's actually a good news story.
It's about the finding by the General Medical Council of Gross Professional Misconduct by Dr David Southall, a prominent expert witness in many child abuse cases. As a result he has been struck of the Register and can no longer practice.
Newsnight takes the angle "Should we trust the expert witnesses?" and as you'll learn from the Lawyer in the piece, he has personally represented no less than 13 sets of innocent parents who have had children taken away and in one case the mother was imprisoned for four years before Southall's evidence was finally discredited. (His accusation in that case had initially been on no more than his viewing of a TV interview with the parents!!)
This is clearly an example where the power of Trusted Surveillance to "prove the negative" would offer parents under this kind of attack an alternative and much more effective defence. If they were able to release key footage demonstrating that they had never performed the kind of abuses they were being accused of, the cases would never even come to court.
Of course, if they were guilty, they wouldn't have a leg to stand on and either wouldn't have bothered recording their domestic "lifelogs" or would simply refuse to release them. At which point, they'll be at the mercy of the expert witnesses...