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Chemistry Expertise in the Courtroom

When does methamphetamine exist in a clandestine drug-lab manufacturing evidence sample? Sometimes it depends upon whom you hire to evaluate the analytical data: a case study.


The information provided below has been taken from an interesting criminal case that occurred in northern California several years ago. The case involved a suspect who had been arrested for possession of methamphetamine and methamphetamine manufacture. Based on materials found at his residence, it was alleged that he was using ephedrine as a starting material in his manufacturing process.

I was asked by the defense attorney acting in that case to serve as a chemistry expert for the court. As such, it was my job to help the attorney learn more about the key chemistry issues in the case, help him formulate questions to ask the other experts during cross-examination, and to use my expertise and creativity to determine if the same chemical evidence might be used to show more than one possible chemical result.

At the outset, the defense attorney’s client argued that he never possessed methamphetamine nor was he making methamphetamine; he just possessed ephedrine powder. At the point I came into the case, the client did not know how the analytical evidence determined by the prosecution’s team could be true; he thought that the police must have made a mistake.


During the course of a drug bust and police investigation of a residence in northern California, detectives discovered chemical substances and solutions that were consistent with those generated when the usual procedures employed for the clandestine manufacture of methamphetamine from ephedrine were used. Key evidence retrieved from the residence included four baggies containing differing amounts of white powders; as well as a quantity of white powdery residue obtained from the face of a small mirror. These items, as well as other evidence samples such as acetone, muratic acid, and two jars containing reddish-brown liquids were confiscated and weighed. Each sample of powder or solution was subsequently analyzed at a local forensic laboratory using a protocol that included GCMS analysis.

​The GCMS printouts indicated that the baggies held different solid compositions, with each powdered mixture containing a detectable, but very low percentage of methamphetamine along with a very high percentage of ephedrine. The ratios of these two materials in each of the samples, however, were shown by GCMS analysis to be different. In the four baggies, these ratios approximately ranged from between 0.5% methamphetamine: 99.5% ephedrine to 5.0% methamphetamine: 95.0% ephedrine.

​The total amounts of substances in each baggie and on the mirror ranged from 1.6g to 7.0g, and the total amount of white powder confiscated was 18.6g. The subject was therefore charged with possession of 18.6g of methamphetamine and was charged with the manufacture of 18.6g of a mixture containing the Schedule II controlled substance: methamphetamine.

​The defendant, if convicted, would be sentenced according to the rules in the Federal Sentencing Guidelines. Conviction for possession and manufacturing of 18.6g of a Schedule II substance would lead to a mandatory jail sentence of 18-24 months.


The different impurity levels and different ratios of meth to ephedrine in each of the baggies and from the mirror residue were said to be because the defendant “had a really crappy method to make methamphetamine so he had to do it over and over again”. But I found this explanation to be unusual, given that someone usually makes one large batch of something rather than doing a reaction repeatedly on smaller scale. If a large batch reaction had been used to make meth, then the amounts of impurities and the ratios of product to starting material would have been constant throughout the samples. Instead, these numbers varied with the samples analyzed and even within the same sample analyzed (see GCMS evidence).

​A comprehensive literature search revealed that ElSohly in the early 1990’s (1) had reported that ephedrine decomposed under certain conditions such as those used by the prosecution’s forensic analysts when they ran their GCMS samples.

Reanalysis of the samples as discussed in the CONCLUSION showed that these samples had decomposed to give a small but detectable amount of methamphetamine and a small amount of ephedrone when the samples were analyzed using an injection port temperature that was too high.

One of the little-known areas where scientists can make a significant impact in people’s lives is in the realm of criminal law. Attorneys, judges, and juries typically have little in-depth knowledge of science, engineering or technology topics, yet our State and Federal courts are mandated to try ALL cases in a fair and equitable manner.

​In order for legal decisions to be fair and equitable to both sides in court cases, each case requires an understanding of all key matters presented by the prosecution and the defense; and this implies that the judges and juries in court cases would possess or have access to useful levels of knowledge about any and all of the highly-technical issues that surrounded and influenced any of the evidence presented at trial. Unfortunately, without the testimony of experts from both sides during criminal cases, this required level of knowledge about technical matters by a court does not occur very often.

​Because of this disconnect between technical matters and court-meted justice, attorneys often hire experts to provide a level of knowledge that can be utilized to explain the importance, validity or actions of each piece of “their side’s” technical evidence.

​In the courtroom, experts can provide a context for results and highlight relevant details as well as explain analytical tests while under examination and cross-examination by attorneys. Without this extra application of meaning or validity to important science-based evidence, juries and judges might tend to ignore or mis-apply relevant science issues, perhaps reaching verdicts based solely upon sections of the testimony that they could understand or relate to in everyday life, rather than on what is truly important. In a case lacking balanced expert evidence, information of a general nature might be used preferentially for decision-making because critical science or analysis issues were misunderstood or ignored.

To keep the latter scenario from occurring, scientists and other experts are brought in to act as educators during courtroom proceedings. Their job is to help jurors and judges understand issues involving scientific data, data analysis and other technical evidence so that all evidence can be properly utilized for the determination of guilt or innocence — based upon all the facts.


This criminal case furnishes us with a great example of the role that experts can play in our legal system. Clearly, input by a chemist who was new to the case produced a large change in how the prosecution and defense interpreted an earlier set of GCMS findings. This change in data interpretation ultimately led to a much different outcome for the defendant than that predicted using the original set of assumption.

In this case, a chemist’s experience in organic synthesis and product isolation, in combination with his recognition of the fact that analytical methods are always imperfect eventually drove him to question the absolute validity of the GCMS data initially provided by the forensic lab.

Given that GC injection ports are heated to high temperatures and that only traces of methamphetamine were detected in the various evidence samples, the expert postulated that the hot injection port on the GC might be causing small and varied amounts of each injected ephedrine aliquot to decompose, forming the methamphetamine that was later detected by the mass spectrometer.

A search of the research literature eventually led to the discovery that a description of this same decomposition process had been published several years earlier and that pure ephedrine, under certain conditions, was known to yield false-positive results when using GCMS analysis.

Communications with the forensic lab chemists who performed the GCMS analyses and the attorneys involved showed that this fact was unknown to them. It was agreed that all samples should be re-analyzed using a set of literature conditions which had been reported as effective for accurate GCMS analysis of ephedrine. Re-analysis of all samples comprising the white powder showed that the confiscated samples in the baggies and on the mirror were ephedrine; none of these contained a detectable amount of methamphetamine when analyzed using the new GCMS conditions. Consequently, all manufacturing and possession charges against the defendant were dropped.

​One of the services that experts in the chemical field can provide to experts in our legal system is access to technical knowledge. Expert knowledge in a science or engineering comes from many years of training, and such expertise, especially in a field like chemistry, can be a valuable commodity when properly applied to evidence and other science issues that arise in practice of the law.

As can be seen in the above presentation, when an attorney can take advantage of a scientist’s in-depth knowledge of subject matter and draw more accurate conclusions about a case, it allows our judicial system to work better. This can be true even in cases where only a small increase in understanding is made: if the new level of understanding allows a judge or jury to make a more-informed choice when weighing the evidence and determining the verdict, the justice system ultimately benefits.

1. J Anal Toxicol. 1992, 16(2):109-11; A procedure for eliminating interferences from ephedrine and related compounds in the GC/MS analysis of amphetamine and methamphetamine. elSohly, MA: Stanford, DF: Sherman, D; Shah, H; Berno, D; Turner, CE.

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