Now we are seeing another difference between the UK courts and the US courts.
Earlier we heard from a forensic psychologist giving evidence for Depp. Her evidence was exactly what Depp would have wanted it to be. Now we are hearing from a forensic psychologist giving evidence for Heard. Her evidence is exactly what Heard would want it to be.
As expert witnesses, their first duty is to the court, not their client. They are supposed to give their honest opinion to the court, not tailor it for their client. They should be impartial and objective. That is true in both the UK and the US. However, the evidence of these witnesses is so tailored to their respective clients that it raises real questions as to whether they are being impartial and objective. If this was the UK, it might raise questions about whether they should be allowed to serve as expert witnesses in future cases.
However, the big difference is that, in the UK, these experts would have been expected to work with each other, agree as much as possible between them and provide the court with a document setting out the areas of agreement. They would then also provide documents setting out the areas where they disagreed. This allows the proceedings to concentrate on the areas of disagreement rather than spending time questioning the experts about the areas where they agree.
In this case, with such wildly differing views on Heard's mental health, the jury will have to decide which expert they find more credible (or decide to ignore both of them).