Did you know that DUI Blood Tests in Arizona Can Be Inaccurate?
by Aaron Black • October 03, 2019
Drawing blood in Arizona to prove the level of alcohol in a person’s bloodstream seems like a sure, scientific system to absolutely show every time that someone was driving while intoxicated.
But it just seems that way.
In fact, blood testing to determine the blood-alcohol concentration (BAC) is not infallible. Blood sample results can be challenged by the defense on scientific, handling, and procedural grounds.
An Officer may Legally Choose a Draw BloodAt the traffic stop the if investigating officer suspects a driver is impaired at or beyond the illegal 0.08 percent BAC and if the driver refuses a breathalyzer test, the refusal means a suspension of the privilege to drive. The officer then can order a blood test.
In Phoenix, Arizona and surrounding communities, certain DUI enforcement officers have been trained in the procedures for drawing blood and some are certified phlebotomists. Or a van staffed and equipped to draw blood may be summoned to the traffic stop scene. Otherwise the suspect is taken to a police station or hospital where blood can be drawn.
To prove BAC accuracy, the blood must be drawn within two hours under Arizona law. If a suspect refuses a blood draw, which also results in a license suspension, the officer must obtain a search warrant from a judge. With today’s technology that can be accomplished within a short time, but not always.
If the blood draw occurred after two hours or longer the authorities can call in chemists and toxicologists to use a scientific and mathematical process called “retrograde extrapolation.” Even if no alcohol was detected after several hours, retrograding determines what the BAC level had been within two hours and the results will be used against the defendant.
Potential Issues with DUI Blood Tests
- The blood draw: Blood is drawn into a vacuum sealed tube, called a vacutainer, and they come with a variety of additives inside for different types of analysis. They have chemicals intended to prevent bacterial contamination and clotting. Improper handling of vacutainers and using those that have seals beyond their expiration dates make them unreliable in preventing contamination.
- Hospital blood tests: Blood taken in this setting is medically based, but to determine an accurate BAC level requires extra steps that forensic labs take in reaching a BAC level.
- Collecting blood samples: Technicians who draw blood can make mistakes that can change the results. For example, if they use alcohol to clean the injection site, which may eschew the results that negatively impact the defendant.
- Procedural problems: The prosecution must be able to establish a “chain of custody” to admit the blood test results into evidence. This chain shows where the sample was at all times between collection and recording the test results and who had charge of them along the process. Omissions or data errors can lead to disallowing the blood to become evidence against the defendant.
- Laboratory and equipment errors: Many forensic labs get much of their business from law enforcement so they may be inclined to produce test results that are favorable to the prosecution. There have been cases in which blood samples have been switched or intermingled either accidently or intentionally.
Testing equipment must be calibrated and properly maintained to render accurate results. But some forensic labs don’t have the money to properly staff and equip the lab, and the labs don’t always have sufficient oversight.
- Storage problems: The time passing between collecting the blood and using it as evidence can be quite lengthy, up to two months and perhaps longer. Blood samples that aren’t properly stored between collecting, analyzing and storing the samples can taint the sample by fermentation. Fermentation of the blood sample produces alcohol in the vial and that results in a much higher BAC level.
Getting Blood Tests into EvidenceGetting blood draw results into evidence requires identifying each person involved and their qualifications in collecting the blood, analyzing the sample, and producing documents detailing the time, date, location and the circumstances in collecting the blood sample.
Records attesting to the calibration and maintenance of equipment and method used in testing the blood are also necessary.
In Your DefenseIt’s customary at the blood draw to take enough to provide the DUI Defense Attorney with a sample for independent testing to refute the test results obtained by police. The goal is to develop a reasonable doubt of guilt and win a dismissal. The defense will bring in experts to challenge the personnel involved in the blood draw and the analysts who determined the results.
I recommend that you request an independent blood test after the police have obtained the blood/breath sample from you. By law the Police must give you the opportunity to make arrangements for the test if you have to remain in custody.
All cases have particular circumstances that can be defenses. For example, if police didn’t have probable cause or reasonable suspicion to make the traffic stop, that’s a violation of your Fifth Amendment right protecting you against self-incrimination.
You also have the right to have an attorney representing you and you must be told that you have the right to remain silent at the arrest.
It’s uncomfortable to decline to answer the officer’s questions at the traffic stop but anything you do say will be used against you so it’s best to politely decline.
Ramifications of a DUI ConvictionA DUI charge in Phoenix, Arizona and surrounding communities can be either a misdemeanor or a felony depending upon the BAC level and other factors, but each has ramifications in regards to your freedom.
- Community service
- Loss of the driving privilege
- A criminal record that can make life difficult to get or hold a job
Free, Comprehensive Legal AdviceAs an experienced and aggressive DUI defense attorney I provide a free case assessment to gauge the strength and faults of the state’s case.
I’ll listen to your side of the event, answer and ask questions, explain the law and the processes involved and your what your options may be.
Contact Phoenix DUI Defense Attorney, Aaron Black to discuss your situation in confidence or call (480) 729-1623 at any time day or night, weekdays or weekends and I’ll promptly respond unless I’m in court.
I defend DUI cases in all Arizona City, State, and Federal Courts.