I understand excatly what you're getting at. And, no I can mount a pretty good challenge against any so-called martial arts expert's opinions because there's always positives and negatives to anyone's training, experiences or biases. This forum is a perfect illustration of that point. I guess the point is based on the rules of evidence, anyone with a black belt (or the equivilent) is potentially competent to be admitted as an expert and allowed to express opinions in a case, but the weight of the expert and the testimony is what is key. Being considered an expert witness doesn't mean diddly if the judge or jury rejects your opinions.