What seems to be happening now is that Nel is attacking Derman's credibility as an expert witness (I believe he stands as an expert and not a lay-witness).
Derman cited a report into the vulnerability of disabled persons, and said they were a percentage more likely to be attacked than able bodied persons.
Nel points out that in the report, it states that the study crossed across all forms of disability, so both mentally ill and physically disabled. The majority of those attacked were mentally ill and were attacked by a carer or family member. He asks why Derman did not clarify those findings when he chose to bring the report to the court.
He also asks him to clarify how much less vulnerable Oscar was when he was holding a gun, which of course Derman cannot do (I'm not even sure it's quantifiable).
He did get Derman to say categorically that OP had the option to walk out of the bedroom door. Derman insists he cannot flee in the way other people might, but Nel puts it 'he could walk out the door in the way that he walked into the bathroom to brush his teeth, for example' which Derman says he can. Again, it's a point that Derman qualifies 'I don't want to put it that he can flee...'
To my mind, Derman would be doing better if he could just state simple yes or no comments, and would stop trying to drive certain points in certain directions. It makes him look biased. Even if he's not actually biased, his pushy and slightly belligerent attitude towards Nel makes him look so.
Sorry - I was compiling an application form when that was going on, so Member may be able to tidy up some of those points.