The US supreme court ruled a few weeks ago that the chemists that perform tests in forensic analysis are not immune from cross examination by defense attorneys. It’s not surprising that the American judicial system did not inherently allow for this, since it’s a very biased and fucked up system. With this tool in the briefs of attorneys, it sets up a very real and very likely chance that a number of methods used in forensic science, as conducted in the state crime labs, will not hold up to scrutiny. Not because they’re necessarily invalid (though, we shall see about that), but because they’ve not been done with the appropriate controls – an argument mentioned in the majority arguments by Scalia:
He cited one report, for example, that said “there is wide variabiility [sic] across forensic science disciplines with regard to techniques, methodologies, reliability, types and numbers of potential errors, research, general acceptability, and published material.”
Putting the chemist or lab technician on the stand to be tested by cross-examination, the majority said, will help “weed out not only the fraudulent analyst, but the incompetent one as well.
While this is a good thing for people who are accused of crimes they didn’t actually commit, it provides a way for a young, naive lawyer to get unfortunately schooled in a cross examination. Without knowing the fundamental questions one should ask (and know before you ask) this could be a strategic blunder, making the forensic evidence look all the more compelling.
So, then, what should a young lawyer who suddenly learned they have this new power look for? Frankly, I don’t know – but I can say there are somethings they should be aware of:
TLC (thin layer chromatography) is not a quantitative method because commercially obtained plates do not contain a consistent density and quality of silica, which means any TLC results are suspect without a co-spot. Even so, co spotting can be misleading, unless you’re using the correct visualization method, to make sure you don’t have any overlapping spots. In effect – I’d thing TLC evidence would be the easiest to toss out and make fun of as a method to corroborate a story. It may be good enough to test purity for a rough guess, but it’s not accepted in the journals as proof – because it’s not.
MS (mass spectrometry) can be misleading since calibration of the instrument must be done correctly. Any competent technician will give the method of calibration. I would guess that state labs use old equipment and they very would could be passing off aberrant noise as a peak of some sort.
Actually, I have to assume most of the stuff they’re doing is done on really old equipment – though that in itself isn’t reason to suspect the results. Questions regarding the validation of that equipment, however, is appropriate. Most scientific instrumentation loses some degree of precision as it ages, rendering it less accurate at the extremes of its detection ranges. External companies are often used (and are usually necessary) to validate the instruments to some specification (I assume NIST standards) and provide proof of that validation. Equipment that lacks this validation may not necessarily provide reliable evidence. If a case could result in a very long incarceration of someone who may be innocent, the calibration – even in a reasonable range of detection, should be a concern.
GMP protocols probably will provide a better guide than I could. I assume if it’s a standard by which drugs are made, it should be a standard by which evidence is measured….