This written appellate opinion sums up the challenge of “gatekeepers” (the judges) at the trial level filtering out expert witness bombast of opinion from actual scientific “causation.” The bombast in the forensic field of testimony can be seen in the hair, bitemark, psych profilers, bullet lead matchers, and not a few rogue blood pattern reconstructionists.

Here’s the clear distinction courts should conceptualize: (It’s in the last sentence).

Of course, its a Canadian court. 

Thanks to Emma Cunliffe at UBC.