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Challenging Blood Tests In Washington State DUI Cases

When Facing DUI Charges

When faced with DUI charges, many people erroneously believe there is nothing they can do. Faced with a chemical blood test, they may believe pleading guilty is their only option. Nothing could be further from the truth. There are a number of steps required to prove a DUI case. From the condition of the tubes used to collect the blood process used by the lab, the state has the burden of proving that its evidence against you is accurate and reliable. DUI cases can be challenged--if you have the experience needed to properly evaluate the strength of the state's case.

Challenges to Blood Tests in DUI Cases

There are any number of ways a qualified criminal defense attorney might challenge the accuracy and reliability of DUI blood test results in DUI cases. Below are just a few areas an attorney may review in order to determine if there is a legitimate basis to challenge a blood test result.

Issues Pre-Blood Draw

Pre-blood draw procedures to exam in blood tests include, but are not limited to the following:

  • Was the person who drew the blood (phlebotomist) approved to take blood in Washington State?
  • Were the collection tubes properly labeled?
  • Did the phlebotomist properly sanitize his/her hands? Bacteria can be an issue in blood tests and improper hand cleaning can contribute to this.
  • Was the site of the blood collection properly cleaned and air dried? Was the cleaning agent alcohol-free? Was it anti-microbial?
  • Were the proper test tubes used? What color was the stopper of the test tube? (The color of the stopper is important, as different stopper colors indicate the presence or absence of different reagents, chemicals, and additives, which can impact the reliability of the test result.)
  • Were sufficient preservatives and anticoagulants present in the test tube to prevent clotting, as well as to stabilize the alcohol concentration of the blood to properly reflect the alcohol concentration at the time of collection?
  • What was the expiration date on the tubes?
  • Was the proper sized needle used to draw the blood?
  • Was the needle properly inserted into the vein?

When anything is wrong with the testing equipment or methodology, the test results may be unreliable. A qualified attorney may uncover a deviation from required protocol that may render the test results unreliable warranting a suppression hearing. Alternatively, at trial, the attorney may call these testing discrepancies to the attention of the jury. Testing performed with unreliable equipment or with unreliable collection procedures will necessarily produce unreliable and inaccurate results.

Issues with Testing

The analytic procedure used for the blood test should include a control test. A control test has a “known answer” and is one method of ensuring the instrument is working correctly. It is not enough to run a control. The results of the control must be consistent with the expected result. The test should also include a blank test. The results of the blank test should be zero, meaning that as a blank, no alcohol should be present in the sample. When either the positive control or the blank yields a result other than what was expected, this is an indication the machine is not working properly and the test results are unreliable.

Furthermore, the test should be subject to duplicate analysis. This test, too, must be carefully examined. State law requires that the duplicate analyses are consistent with the first test, within a very narrow range. If the control fails, if the blank shows the presence of alcohol, or if the replicate test result varies too far from the original test result, the result is unreliable. This may go to admissibility, or it may go to weight at trial. In either event, the final conclusion is called into question.

Quality Assurance Issues

In every blood draw case, the collection and sample preservation methods should be reviewed.

  • What steps have been taken to ensure there was no hemolysis? Hemolysis is the process of red blood cells breaking down, which can create alcohol fermentation after the blood is drawn, potentially inflating the blood alcohol test results.
  • What steps have been taken to ensure the tube was free from contaminants, including bacteria? The presence of bacteria could create the presence of alcohol through the process of fermentation after the blood has already been drawn, thus artificially inflating the blood alcohol test results.
  • Was the blood collection tube properly handled, including inverting it after blood collection?
  • Is each person who handled the sample properly trained to handle blood specimens?

In each case, blood alcohol analysts are required to follow certain laboratory protocols. A complete review of the file must occur to ensure compliance with all relevant protocols.

Proficiency Testing and Analyst Qualifications

There are two types of proficiency tests required by Washington state law. First, each analyst must have some of their blood samples exchanged with other laboratories and retested. The purpose of the retest is to evaluate the precision and accuracy of the test method, as well as to confirm the competency of the analyst. Additionally, the laboratory should perform internal proficiency tests on their employees, to ensure ongoing competence.

Analysts must be qualified before performing work as a blood alcohol analyst. These qualifications include college-level training in fundamental analytical chemistry. They must have a minimum of five quarter hours of qualitative chemistry laboratory. And they must have received a passing grade in these classes and labs. Additionally, the analyst must have a permit issued by the state toxicologist. They must be subject to written, oral, or practical examinations so the state toxicologist may adequately judge the qualifications of applicants.

It is important to carefully analyze the process used to test any blood sample. There have been instances both in Washington and in other states where an analyst has been caught forging lab processes or credentials. There have been a number of high profile cases recently where toxicologists from State Toxicology Labs were disciplined for not following required procedures.

Chain of Custody Issues

When a blood sample is taken, the sample passes from the person collecting the sample to a law enforcement officer, who transports it to the laboratory. When the sample arrives at the laboratory, it's received by someone at the laboratory who checks to make sure the sample is properly labeled, is in good condition and documents its arrival. The blood is stored in a refrigerator until it is tested. At the time of testing, it checked out of refrigerated storage, a small sample of blood is extracted from the vile and prepared for testing. Each step of the way, the government must prove the blood was properly transported, stored and handled by each person in the chain of custody.

Gas Chromatograph Maintenance and Calibration

The instrument most commonly used to analyze the blood for the presence of blood alcohol is a gas chromatograph. This instrument is required to undergo a regular maintenance and calibration schedule to ensure reliable test results. Reviewing both the calibration and maintenance logs may yield valuable information about the test accuracy and reliability.


Blood alcohol analysts are human, and therefore, their work is subject to error. Every DUI blood test result must be examined carefully for errors. From using an alcohol wipe on a defendant's skin, to failing to properly store the specimen, errors can and do occur. Sometimes errors may be attributed to a specific laboratory analyst, other times, there may be a larger problem. In any event, when there are errors, the test results themselves are not accurate or reliable.

Using Experts

An independent expert can examine the specific test procedures used to test a person's blood to determine whether the test results are forensically accurate and reliable. An independent expert can examine each step of the process, looking for missteps, skipped steps, short-cuts, or mistakes. Experts may not be hired in every DUI case (over and above the expertise of a criminal defense attorney who understands the scientific issues associated with DUI cases), however, in cases involving blood tests, hiring an expert may be appropriate if the facts warrant it. Hiring a criminal defense attorney who has a relationship with an expert in forensic testing, forensic laboratory audits, and quality assurance may be critical to defending your case.

If You Are Facing DUI Charges

If you are facing DUI charges, you need a qualified criminal defense attorney with specific experience handling DUI cases. DUI cases are unique, as they require both knowledge of the law and an understanding of the forensic science of blood testing. Sheri Pewitt is a member of the National College for DUI Defense and has completed hands-on training in forensic blood testing through the Rocky Mountain Instrumental Laboratories. Sheri Pewitt maintains a close relationship with forensic experts who have the credential necessary both to review the steps taken by the lab, and to testify in court when appropriate. Sheri Pewitt has a proven track record of carefully reviewing DUI cases for both legal and scientific issues which may render DUI blood test results unreliable. She knows when to bring in an expert to analyze the work of the Washington State Toxicology Laboratory. No stone is left unturned when the Pewitt Law defends DUI cases.

Amendment IV

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Amendment VI

In all criminal prosecutions, the accused shall enjoy the right to a speedy and public trial, by an impartial jury of the state and district wherein the crime shall have been committed, which district shall have been previously ascertained by law, and to be informed of the nature and cause of the accusation; to be confronted with the witnesses against him; to have compulsory process for obtaining witnesses in his favor, and to have the assistance of counsel for his defense.