What is a Chemical Blood Test?
What is a Chemical Blood Test?
Whenever a driver is arrested in the State of California for suspicion of DUI, they are then subject to the provisions of the Implied Consent Law. This section of the law is presented in section 23612 of the California Vehicle Code (CVC). CVC section 23612 reads, in part….
A person who drives a motor vehicle is deemed to have given his or her consent to chemical testing of his or her blood or breath for the purpose of determining the alcohol content of his or her blood.
Essentially this means that if a person makes the decision to drive in California, they have implied that they will consent to a blood or a breath test if arrested for DUI. Refusing to submit to a chemical test is a violation of the vehicle code known as a Chemical Test Refusal and exposes the driver to harsher penalties.
Generally speaking, a driver has the right to choose between submitting to a blood or breath test, although a chemical blood test may be compelled by the arresting officer if no breath test device is reasonably available, or if the officer suspects the driver is impaired by something other than alcohol.
A chemical blood test is simply a process by which a sample of blood is drawn into a sanitized blood vial by a trained phlebotomist, nurse, doctor or paramedic. The blood sample is then placed into an evidence refrigerator until it arrives at a forensic laboratory for analysis. Once the analysis is complete, the blood analyst must prepare a report known as a Forensic Alcohol Examination Report (FAER). Finally, the report is forwarded to the DMV as evidence to support the suspension of the accused person’s driver license.
At a DMV Administrative Per Se Hearing, the Hearing Officer will seek to establish that the steps followed in collecting, preserving, and testing a driver’s blood were performed appropriately and that, based on that proper processing, the resulting blood/alcohol concentration must be true. This means that so long as the blood was properly tested, it must be accurate.
Classically, when a driver is arrested for DUI on a street or highway, he or she is advised of the “Implied Consent Law” and they are offered the option of submitting to a blood or breath test. In rare instances, a blood sample may be drawn at the scene by a nurse or phlebotomist who contracts with the police agency to draw blood samples from arrestees. In most instances, however, the arresting officer will transport the driver to a police station, county jail, or hospital for the blood draw.
Procedure for Collecting a Chemical Blood Sample:
- Government Codes and Regulations establish the minimum training and certification of the person who draws a blood sample. Classically the “blood tech” is a phlebotomist, nurse, doctor or paramedic.
- The blood sample must be drawn in a medically approved manner.
- Current law does permit blood samples to be drawn by force in some instances.
- The blood must be drawn in the presence of a law enforcement officer, preferably the arresting officer.
- The driver’s arm should be swabbed with a “non-alcoholic” cleanser prior to the insertion of the needle.
- The blood tech is to draw a sample into a properly sealed, evidential test tube, which contains a certain mixture of an anti-coagulant and preservative powder. The test tube should be properly labeled to indicate the driver’s name, the date/time of draw, and the initials of the phlebotomist.
- The blood vial should be shaken or inverted to thoroughly mix the blood with the anti-coagulant and preservative which has collected at the bottom of the vial.
- In most instances, the test vial is sealed in an evidence envelope to protect its integrity and to prevent the test tube from being co-mingled with other samples. In doing this, the Chain of Custody is established.
- At this point, the blood sample is either retained by the blood tech or released to the arresting officer so that it can be secured in an evidence refrigerator until it is picked up and tested by the county or state crime lab.
- Only those laboratories certified by the California State Department of Public Health may analyze blood samples to be used in criminal and administrative proceedings.
- The forensic laboratory must be in substantial compliance with Title 17 of the California Code of Regulations.
- The Gas Chromatograph used to analyze the blood sample must be routinely maintained and checked for accuracy.
- The “chain of custody” must be maintained to clearly identify any person who possessed the blood evidence.
- Once delivered to the Forensic Laboratory, the blood vial should be protected and stored in a stable environment which normally means in a refrigerated storage location.
- When the first analysis is to occur, the analyst should remove the blood vial from its packaging and makes notations regarding the condition of the blood vial, the expiration date of the vial, any evidence of unmixed powder or any evidence of blood clotting.
- If there is evidence of clotting, the vial should be placed in a device to vigorously shake the sample to emulsify any clots.
- Most often a small portion of blood is removed through the stopper at the top of the vial. The sample to be tested is then introduced into the process of “Headspace Gas Chromatography.” This is a scientific process of separating and analyzing compounds in the blood sample that can be vaporized without those compounds decomposing. The Chromatograph uses a “flow-through” tube known as a Column. As the blood sample is injected into the column, it is mixed with inert compounds to help it vaporize. Different compounds will vaporize and move through the column at different rates. The rate at which molecules pass along the column depends on its rate of absorption. The various components of the mixture are separated as they pass along the column and reach the end at different times (retention rate). By knowing the retention rates of different compounds, the Chromatograph can identify the compounds in the blood sample and their concentration.
- A blood sample should be analyzed twice and preferably by two different analysts. An average of the two samples is computed to estimate the true blood/alcohol concentration.
- Once the samples have been run and averaged, the lead analyst should prepare a Forensic Alcohol Examination Report.
Are Chemical Blood Samples Accurate?
It is widely believed that blood analysis if the most accurate method for determining blood/ alcohol concentration. This belief is based upon the fact that the blood is directly analyzed and therefore, errors that may occur when converting from blood to breath are defeated. In almost all instances, a blood sample is drawn after a driver is arrested and taken to a police facility, county jail or hospital. The delay in time created between the time of driving and the time of blood draw may create a defense, in that; the blood alcohol concentration of a driver, who’s blood is drawn at a police station, will reflect the alcohol level at the time of blood draw, not the time of driving.
A “time of driving” defense may be possible at the DMV, particularly if it can be shown that the blood sample was drawn from a driver more than 3 hours after the termination of driving. This may occur in arrests following an accident, where the time of the accident is not established, or when a driver is arrested at their home sometime after the termination of driving.
“Retrograde Extrapolation” occurs when a Forensic Toxicologist attempts to look back in time to calculate the actual blood alcohol level of a person “at the time of driving.” This is a difficult process that is subject to much difficulty and speculation but, presented properly, it can be a valuable tool in defending your driving privilege.
Even though blood testing is considered the most accurate method for determining blood/alcohol concentration, problems do exist. Blood is an organic substance which begins to degrade the instant it leaves the human body. Hairline cracks in the blood vial; lack of preservative in the test tube, a failure to properly mix the blood sample with the preservative, or the temperature and length of storage can all create problems with the accuracy of blood testing. Blood samples can ferment, clot or degrade. The Gas Chromatograph used to test the blood can be faulty or out of calibration. There have even been instances blood vials have been mixed up with other vials at the forensic laboratory.
Just because the DMV will presume the accuracy of the chemical blood test doesn’t make it correct. Blood sample can be corrupted at the point of collection, storage or testing. Blood samples may only represent the blood/alcohol concentration at the time of testing…. Not necessarily the time of driving.
A quality and experienced DMV Defense Expert will challenge every part of a driver license suspension, including the accuracy of the chemical blood test.
Call US Today to Avoid Losing Your APS Hearing at the DMV.
Challenging the accuracy of a chemical blood test requires advanced knowledge in the area of law, evidence, science and procedure. It is not likely that the average driver in California has the skill set necessary to beat the DMV at the game of science.
The DMV Defense Experts at California Drivers Advocates have been doing precisely this for years. We know where chemical blood samples go wrong. We know how to force the DMV’s case off the tracks. Don’t trust your driver license to someone who doesn’t have the experience to beat the DMV at their own game. Call CDA………We’re ready to help you.
More about Administrative Per Se (DUI) Hearings at the California DMV