Hierarchy of propositions

What are the different levels of information that a forensic scientist can provide from the examination of biological evidence? Can a forensic scientist comment on the guilt of an accused? What does science allow a forensic scientist to opine on? It is essential that judges and lawyers know the propositions on which a forensic expert can comment on, so that they can scrutinise if the expert has overstated their claims in a report. Let us explore these issues with Dr Turbett in this video.

In your experience, do you know instances where a forensic scientist has opined on areas that were beyond their expertise? How did the court respond to such an expert and their opinion?