Tag Archives: Scientific Evidence

DEA Chemists: In Drug Cases, Sometimes They Just Make It Up

I have written before how in criminal drug prosecutions, the government analyst should be cross-examined  and their case file and other information should be requested to prepare a defense case. A colleague sent me a great example of this effort paying off.

D-L Color Test of Three Suspected Marijuana Samples

D-L Color Test of Three Suspected Marijuana Samples

A chemist at the DEA Mid-Atlantic Laboratory wrote in a report that three samples suspected to be marijuana turned purple in a Duquenois-Levine color test. The problem is that the picture of the test (not included in the report but in the analyst’s case-file) showed only one sample that might conceivably indicate the sample was marijuana (and even that one is weak). Continue reading

Who Cares Whether Urine Scores Are Reliable? DC Still Prosecuting Per Se Urine DUI Cases.

Even though everyone in the DC government, from the DC Council to the prosecutors at the Office of the Attorney General, knows that alcohol in the urine has a “loose correlation” to intoxication, that urinalysis is unreliable, people are still regularly prosecuted and convicted of driving under the influence (DUI) base on their urine scores.

Back in June of 2011, DC Chief Toxicologist Lucas Zarwell of the Office of the Chief Medical Examiner, stated under oath to the DC Council that urine testing cannot reliably determine impairment or blood alcohol levels. In response to a question from council member Phil Mendelson, Mr. Zarwell testified as follows:

MENDELSON. How accurate is urine testing for measuring blood alcohol content?

ZARWELL. It’s not.

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Why It’s Important To Get Drug Lab Info In Drug Cases

To live up to its name, forensic science must conform to the scientific method, which the Oxford English Dictionary defines as “consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.” The scientific method seeks above all to prove or disprove hypotheses through testing in order to determine whether a particular conclusion is reliable. If recent history has taught us anything, it’s that forensic science often falls short of this ideal. But we as criminal defense lawyers can’t expose these failings without better information on lab procedures. I have written about cross-examining drug experts here. Continue reading

In Drug Cases, Cross-Examine that “Expert”!

I was in court just before the Christmas break, waiting for a chance to talk to the clerk, and I got to see part of a colleague’s misdemeanor marijuana possession trial. I was very disheartened to see that when it came time for the DEA chemist’s testimony, the defense lawyer did not challenge her qualifications, did not challenge the identification of the seized evidence as marijuana, and did not cross-examine the chemist at all, not even to have the chemist at least list the procedures performed, etc. Continue reading