In What are the qualifications to be an expert witness?, David Goodwyne writes:
What are the qualifications required to be an expert witness? There is no hard and fast rule or one size fits all standard checklist which a potential expert must achieve in order to be selected or qualified as an expert witness. Here are just some of the basic guidelines:-
(a) Education background – Ideally, the expert witness should have the relevant academic qualifications from a recognised university. For example, it would be of little use if a forensic “expert” apparently got an online degree from a non-existant university. There have been instances where “experts” of this nature have been ripped to shreds – in fact, there was a recent case where the attorney managed to demonstrate that even his dog could have obtained the degree (and with higher marks!).
The education background of the expert has to be similarly impressive. If he only has a diploma in an unrelated field, then frankly, he is not going to be impressive or a worthwhile expert.