This case follows closely on the heels of a similar case that I wrote about a few years ago (the Melendez-Dias v. Massachusetts case). In that case, the Court found that a report from an analytical lab could not just be submitted as incontrovertible evidence, but that the defendant had the right to question the person who prepared it.
In the newest case, the Supreme Court clarified that last sentence to mean that you have the right to question the person who prepared it. Literally. Not their supervisor or another colleague, but the actual person who did the work.
I am all in favor of this, and can't see why anyone with scientific training would be against it. In any measurement, there are always a number of things that can go wrong, and the court knew this. A specific example was given in footnote 1:
"In order to perform quantitative analyses satisfactorily and . . . support the results under rigorous examination in court, the analyst must be aware of, and adhere to, good analytical practices and understand what is being done and why...Even after the machine has produced its printed result, a review of the chromatogram may indicate that the test was not valid. Nor is the risk of human error so remote as to be negligible. Amici inform us...a single forensic laboratory produced at least 206 flawed blood-alcohol readings over a three-year span, prompting the dismissal of several criminal prosecutions...An analyst had used improper amounts of the internal standard, causing the chromatograph machine systematically to inflate BAC measurements."(I removed all the references so as to make the quote more readable. Isn't it cute that she calls the GC a "machine"?)
What really bothers me though, are the arguments against having the analysts defend their work. Again from footnote 1 (yes, it was one big footnote):
"...the State presented testimony that obtaining an accurate BAC measurement merely entails “look[ing] at the [gas chromatograph]machine and record[ing] the results,”..."Merely?! Merely?! Merely?! Unbelievable. Any junior-level chemist-in-training can punch a dozen holes in that argument, and yet 4 justices agreed with that argument.