I enjoyed Cliff Hutchison’s post at the ScienceEvidence Blog (cleverly titled Don’t Bogart That Expert) about the qualifications of a marijuana defendant’s expert witness.
The case discussed involved a former criminal defense lawyer who was an opponent of the drug war, who had been qualified in 100 marijuana cases to testify as an expert witness, always for the defense. The court eventually ruled that the defense had not properly established his qualifications as an expert in the field.
However, they rejected the Government’s theory that his testimony was more prejudicial than probative, simply on the basis of his bias against our current system of prohibition and incarceration. Cliff questioned that part of the finding:
Query, though, if the government wasn’t correct in arguing that an advocate witness has no business offering Rule 702 testimony? Logan claimed to have testified in over one hundred marijuana cases, and if his testimony was consistently an argument favoring marijuana defendants, how can it be considered reliable? The testimony becomes simply bolstering, in the guise of expert opinion, hence not helpful to the fact finder.
I have to jump in and disagree here. Let me make my point by using some obvious and common examples from the prosecution. Would this mean that the Austin Police Department’s DWI Task Force officers, who are qualified as experts in the standard field sobriety tests based on their NHTSA training, would be disallowed if it turned out they always testified for the prosecution? (I assume it’s self evident that they do.) If I could just get them disqualified, I'd probably win every case...