Gas Chromatography, DWI, and Me

I was an English Literature major at Rice University. I have always believed, and have always counseled young people determined to go to law school, that an undergraduate degree in English is the best preparation for law school. At Rice, I learned how to read analytically and write well. If you can do those two things, it’s hard to do poorly in law school. It certainly carried me through three years at one of the most competitive law schools in the country, The University of Texas School of Law, while working 20-30 hours a week at a small criminal defense firm to pay the bills, as I was on my own getting through college and law school. The time necessary to work and survive financially certainly detracted from the time demands of law school. So, reading analytically and writing well helped immensely to make up the difference.

It never occurred to me to tackle science. I did not take chemistry in high school (which I didn’t really attend, but that’s another post) or in college. I did take “Concepts of Physics” and “Space Colonies” at Rice, but that is and was the extent of my exposure to things scientific when I entered law school. It wasn’t until I began trying cases as a young prosecutor that I discovered that I had an actual aptitude for science. In my career as a prosecutor and as a criminal defense attorney, I have direct-examined and cross-examined scores of technical, medical, and scientific experts in the presentation, prosecution, and defense of criminal cases: medical examiners, neurosurgeons, forensic scientists (DNA and such), chemists, technical supervisors, psychiatrists, psychologists, statisticians, mechanical and electrical engineers, handwriting analysts, trace evidence analysts, firearm and tool mark examiners (what laypersons call “ballistics”), and a host of others. In each case, a working understanding of the science and technique underlying the science in question was necessary to effectively present technical evidence to a jury or cross-examine an expert presented by the opposing side. And, frankly, such an understanding is vital to being able to recognize junk science and faux experts when confronted with them in court. And, it happens far more often than most people realize.

Over the past several decades, many citizens have been convicted and imprisoned, some even sent to death row, based on “expert” testimony with little scientific foundation. In obtaining convictions, prison sentences, and death sentences, prosecutors across the country have relied on “bitemark” evidence, vague arson forensics, “lip print” testimony, “expert” aging of bruises, hair and fiber analysis, and other similar evidence. There has been increased scrutiny on these “forensic sciences” used in criminal cases since the advent of forensic DNA comparison technology in the mid-1980’s. In fact, DNA testing has cleared hundreds of wrongfully convicted defendants, including scores sitting on death row, in the past 10-15 years. After an attorney in Oregon was wrongfully arrested for the Madrid train bombing about 10 years ago based on an incorrect fingerprint match by the FBI, Congress commissioned an extensive study of forensic sciences by the National Academy of Sciences. The resulting report, which can be found here, rocked the scientific and forensic worlds. Things were not as they should be, according to the panel of nationally acclaimed experts in every forensic and scientific discipline. That study has led to an increased scrutiny of forensic “experts” and laboratories across the country, highlighted by one forensic lab scandal after another.

The bottom line: the reliance on forensic science in the criminal courtroom in America and Texas requires constant vigilance and skepticism. The single-most significant obstacle to this endeavor is the lack of meaningful oversight of these alleged “experts” and their forensic opinions, and that includes prosecutors, judges, and jurors.

And, most of all, criminal defense attorneys.

It is ultimately the obligation of criminal defense attorneys to challenge, at every turn, the use of forensic science in the criminal courtroom. Not because there is no validity to any of these forensic disciplines, but because there is such an unacceptably high occurrence of the use of unfounded and unscientific evidence in the courtroom and of unqualified or barely-qualified government experts. And, if criminal defense attorneys do not challenge the validity of scientific evidence and the techniques and methods employed by those offered as experts, then our judges and juries will simply assume that the testimony is golden and the person sitting next to the defense attorney to whom the prosecutor points accusingly in closing arguments is guilty. So much for the presumption of innocence.

And now, to the point of this post. Finally.

I recently completed the Forensic Gas Chromatography Course in Chicago, a week-long intensive class on the science of chromatography. Chromatography is the science and laboratory technique for separating the components of a mixture into separate parts so that they may be measured. It is a discipline of analytical chemistry. The key to understanding this science is to appreciate that it is all about separation. It is accomplished through the use of a chromatograph, either gas or liquid, a laboratory instrument considered the gold standard in the science of chromatography.

During the week in Chicago, there was math. There was chemistry. There was physics. I learned how much I did not know about science. And I am a much better attorney for having gone through the course.

Why did I go through this course? Because a significant percentage of my criminal defense practice is the defense of DWI cases. These days, it is rare, especially in Brazos County, to be retained on a DWI case that does not involve a blood draw and blood analysis for alcohol concentration. In the past, if a citizen arrested for DWI refused to provide a specimen of his or her breath or blood, then none was taken, what was referred to as a “no-test” case. Now, with the advent of “fill-in-the-blank” search warrants, a warrant can be obtained and executed in less than an hour. So, blood is drawn in almost every DWI case, either by consent or by search warrant. It is even becoming the case that arresting officers are not even offering a breath test to arrested citizens. So blood analysis for the concentration of alcohol is a part of almost every DWI going forward.

And how do they test blood for alcohol concentration? Gas chromatography. More specifically, head space gas chromatography with flame ionization detection. In Texas, blood is analyzed in government labs using this instrument almost exclusively. So, a criminal defense attorney handling DWI’s should know about the science underlying chromatography and the proper methods and techniques in the process of separation and measurement of alcohol concentration in human blood.

It has been my experience that many people, criminal defense attorneys included, believe that blood analysis is infallible and DWI’s in which blood analysis was conducted should always result in a plea bargain. They are wrong. Any instrument can fail. Science and technology have not reached the point where we can say it is always right. And, most importantly for our purposes, the process and method of applying the science, including the qualifications (or lack thereof) of the persons running the instrument, are vital to valid results.

The course was amazing. It is conducted by Axion Laboratories of Chicago in conjunction with the Chemistry and Law Division of the American Chemical Society. The course is taught by several highly qualified instructors including Harold McNair, one of the founding pioneers of chromatography science and the first person in the United States to obtain a Ph.D. in chromatography. Professor Emeritus McNair literally wrote the book “Basic Gas Chromatography,” considered one of the authoritative texts on chromatography. And, I have a personally autographed copy to prove it. Professor McNair is 82, but is still one of the sharpest minds I have met. Axion Labs was founded by one of his earliest protégés, Dr. Lee Polite, also a Ph.D. in chromatography. Finally, the faculty is rounded out by two of the best DWI attorneys in the country, Justin McShane of Pennsylvania and Josh Lee of Oklahoma.

I still have a lot to learn, but, as Drs. McNair and Polite emphasized over and over, I probably know more about chromatography now than 90% of the “scientists” working in government labs in Texas and around the country (as do all of the other attorneys who have gone through this course, only 200-300 across the country).

Having said all that, here are some interesting “take-aways” from the course and from my DWI practice:

While almost 10 milliliters of blood (a small tube) are routinely drawn in most DWI cases, only about 200 microliters are actually tested. A microliter is one millionth of a liter, or one thousandth of a milliliter. It is but a fraction. This is important because as the sample gets smaller, any error is exaggerated significantly.

They don’t actually test the blood. In head space gas chromatography, what is actually being tested is the vapor above the minute blood sample in a closed “head space vial.” This form of testing is based on the scientific theory that equilibrium between the substance and the headspace above the substance will be achieved at some point when heated at a constant temperature. Simply put, the closed vial with the minute sample of blood is heated to a constant temperature for a period of time and a sample of the vapor is extracted and injected into the gas chromatograph for analysis. So, it is not actually the blood that is tested. This method avoids “gunking up” the chromatograph with blood and other substances.

Temperature is everything. If the temperature is off at any of several points in the process, the test is invalid or may report significantly higher blood results than the actual alcohol content in the blood. How do we know that the temperature at these points is acceptable? The machine tells us so. And machines, of course, never fail.

The gas chromatograph, when first uncrated, has no idea what ethanol looks like. The instrument has to be taught to recognize ethanol. The process to “teach the machine” and to maintain its calibration is critical and rife with potential error. Again, it depends on the qualifications of the persons “teaching” and operating the machine. Which leads to the next very important point…

Most “forensic scientists” working in government crime labs have no prior experience with the gas chromatograph or with chromatography. I have yet to meet the government lab “scientist” who actually has a degree in chromatography or even the more broad discipline of analytical chemistry. Most have a bachelor’s degree in chemistry and no practical experience in chromatography. Usually, they are taught “on the job” by other persons with similar experience. These are the people “teaching the machine,” setting up lab protocols for process, calibration, and quality control. They are, effectively, button pushers. The gas chromatograph does all the work. But, the results are only as good as the technique by which it is operated.

The “forensic scientists” in government labs will tell you often and emphatically that they are “neutral” and unbiased. Nonsense (I really want to use a stronger word, but this is a family blog). They are government or law enforcement agency employees paid by the government. They work closely with prosecutors. They are trained on how to effectively testify in court. They play games in responding to defense subpoenas for their lab files, calibration and maintenance records, and lab protocols (you have to ask just right or you don’t get what you need, which is why the kind of training I just finished is important for DWI attorneys). And, in my experience, they will go out on limbs that legitimate scientists would not in order to support the State’s case.

Blood samples are tested in batches of between 30 and 60 at a time. This is accomplished through the use of a machine known as an auto sampler. Numerous vials are loaded on to the auto sampler and then the “scientist” pushes a button, often right before they go home for the night. So, when tested by the gas chromatograph, there is often no one in the lab at all. Blood vials are sampled one after another, each taking between 6-10 minutes.

Probably the most troubling aspect of this method, or at least the method employed by most crime labs, is that there is nothing between samples to insure that there is no “carryover” from one sample to the next. In an ideal laboratory setting, there would be a “blank” between each sample. A blank is a known sample that contains only an internal standard used by the laboratory. Without getting into specifics, the purpose of the blank is to make sure that there is no residual contamination, including ethanol, from blood vial to blood vial. In an ideal situation, a blank should be run between every sample. It may take a little longer in the sample preparation phase and in the chromatograph batch run, but hey, we’re only talking about whether a citizen is prosecuted using evidence valid beyond a reasonable doubt, so it’s good enough for government work. Not good enough. A DWI conviction, even a probation, will affect a person for a lifetime. It is not too much to ask that we expect standard lab protocols used everywhere else in the scientific community when it comes to convicting a citizen of what has become a toxic misdemeanor offense, or sending citizens to jail or prison. The problem is that most crime labs, especially the Texas DPS crime lab, are inundated with blood samples due, again, to the advent of “fill-in-the-blank” blood search warrants. So corners are cut because of budget and time constraints.

The headspace gas from the blood sample is injected into the gas chromatograph and introduced into what is known as a “column.” The column is the heart of the gas chromatograph. It is a very long, very slender tube (not much bigger than a human hair) that is coated on the inside with substances with which different substances react differently.

What identifies the unknown substance to the trained scientist is the amount of time a substance takes to pass completely through the column (known as “retention time”). The column is usually about 30 meters long, give or take a foot or so. When a substance “elutes” from the end of the column, it is burned up by a flame which generates an electrical signal that can be plotted and measured. The flame is the “flame ionization detector” or FID. As it generates the electrical signal, the data is sent to a laptop computer which generates a “chromatogram,” a graphical representation of the retention time (the time it takes substances to go completely through the column) and the amount of the substance as represented by a series of peaks on a chart. It is the area under the peak, along with other data, that results in a blood alcohol concentration. Knowing how to read a chromatogram is critical to an adequate DWI defense. The most important point to be made about the column is that it must be heated to and maintained at a constant temperature. Remember, temperature is everything.

The validity of a result from a gas chromatograph is a function of how the instrument is calibrated. To calibrate a gas chromatograph, a calibration curve is generated using several known ethanol samples. Once generated, the calibration curve is vital to the analysis of every sample. If the calibration curve is not performed properly, nothing that comes out of the instrument is scientifically valid. The number of points (or known samples at different ethanol levels), whether zero is used as a calibration point, and how often calibration curves are performed is a constant source of tension between government lab workers and knowledgeable DWI attorneys. The bottom line is that if the forensic scientist does not adequately and validly construct a proper calibration curve on a regular basis, the results of the instrument in question cannot, or should not, be relied upon in court… And:What identifies the unknown substance to the trained scientist is the amount of time a substance takes to pass completely through the column (known as “retention time”). The column is usually about 30 meters long, give or take a foot or so. When a substance “elutes” from the end of the column, it is burned up by a flame which generates an electrical signal that can be plotted and measured. The flame is the “flame ionization detector” or FID. As it generates the electrical signal, the data is sent to a laptop computer which generates a “chromatogram,” a graphical representation of the retention time (the time it takes substances to go completely through the column) and the amount of the substance as represented by a series of peaks on a chart. It is the area under the peak, along with other data, that results in a blood alcohol concentration. Knowing how to read a chromatogram is critical to an adequate DWI defense. The most important point to be made about the column is that it must be heated to and maintained at a constant temperature. Remember, temperature is everything.

Just because the government says it’s so, doesn’t make it so. And just because you wear a white lab coat doesn’t make you a scientist.

And there are lots more. I enjoyed the course immensely and feel privileged to have learned from some of the country’s best authorities on the subject of gas chromatography. Axion Labs offers two more courses on the use of the chromatograph and another instrument called a mass spectrometer (for use in analyzing unknown substances for the presence of illegal controlled substances) in forensic science, both of which I will attend in the coming year. There is no question that I am a better DWI attorney for the experience.

Knowing the underlying scientific principles of forensic sciences is important to the criminal defense attorney because the only people who are challenging, questioning, and confronting the questionable use of forensic science in the courtrooms of America are criminal defense attorneys.

Not bad for an English major, if I do say so myself. Which I do.