Driving under the influence (DUI) is a severe criminal offense with significant legal consequences, including fines, jail time, and a permanent criminal record. Blood testing is one of the tools law enforcement uses to determine whether a driver violated the law. DUI blood testing involves collecting a sample of a driver's blood and analyzing it for alcohol and/or drug content.
Understanding the collection and analysis of blood samples in DUI cases is critical for defendants facing charges related to DUI. Blood testing is considered a more accurate method of determining a driver's impairment level than other testing types, such as breath or urine tests. However, various factors can impact the accuracy of blood test results, including the collection and handling of the sample, the calibration and maintenance of the equipment used for analysis, and the experience and training of the technicians performing the analysis.
Defendants facing DUI charges should understand how blood samples are collected, how they are analyzed, and how to challenge the blood test results if necessary. With a clear understanding of the collection and analysis of blood samples in DUI cases, defendants can work with their attorneys to mount a strong defense and protect their legal rights.
The Collection of Blood Samples
After being stopped for a DUI, the defendant may be brought to the hospital if law enforcement or EMTs decide the defendant may need medical attention. While at the hospital the medical staff may take a sample of the defendant’s blood for a broader range of tests but including toxicology screening. While most medical recprds are considered private, the prosecutor will often subpoena those records later. The prosecutor must provide notice to the defendant that they intend to ask a judge to issue a subpoena for their medical records. They merely have to demonstrate to the judge that the collection of the defendant’s medical records are relevant to their investigation.
However, if law enforcement officer has probable cause to believe that a driver was operating a vehicle under the influence with serious bodily injury, they can require the Defendant provide a blood sample.
The purpose of the test is to determine the driver's alcohol concentration level or the presence of a controlled substance.
Regarding collecting blood samples for DUI testing, following proper procedures to ensure the sample's integrity is critical. This is because the slightest contamination by microorganisms or other foreign substances can significantly impact the accuracy of the results.
Blood samples must be collected for DUI testing by authorized personnel properly trained to carry out the procedure. During blood sample collection, it's essential to sterilize the puncture site and the equipment used to prevent contamination. Additionally, it's important to properly preserve the sample to prevent fermentation, which can cause the alcohol content to rise over time. The specimen should be refrigerated as soon as possible after collection to ensure its integrity.
A breakdown in the chain of custody could also compromise the reliability of the results. This could occur if the sample is not labeled correctly or stored or if gaps exist in the documentation of who handled the specimen from when it was collected to when it was analyzed.
The Analysis of Blood Samples
Once a blood sample has been collected, it's sent to a laboratory for analysis. The most common method used for this analysis is gas and liquid chromatography.
Gas chromatography separates the different compounds in the blood sample as they travel through a chromatograph column. Each compound elutes from the chromatograph at different times. The process allows technicians to identify the specific compounds present in the blood sample and determine the level of alcohol or drug content.
Despite its accuracy, several potential sources of error can impact the analysis of blood samples:
- Contamination during the blood draw process: If the puncture site is not properly sterilized, it can introduce foreign substances that can impact the results.
- Contamination during the analysis: The equipment used in blood testing includes needles and syringes. Contamination of these items can introduce bacteria or other microorganisms into the blood, interfering with the measured chemical reactions.
- Contamination of the vial: The vial used to collect blood for testing must be sterile and free of any contaminants that could affect the accuracy of the test results. Contamination can occur in several ways, such as when the vial is not sealed correctly or when the blood is collected in a vial that has been previously used.
- Contamination of the Chromatograph: If the instrument is maintained properly, the results may be contaminated which can often be identified in the chromatogram, or the printed material reflecting the testing process and results.
The Role of Expert Witnesses
Expert witnesses are typically forensic scientists or chemists with extensive training and experience in analyzing blood samples for alcohol and drug content.
One of the primary roles of an expert witness is to help the defense team understand the technical aspects of blood sample analysis and identify potential sources of error or contamination. They can also help to challenge the validity of the results by reviewing the laboratory's procedures and protocols, analyzing the data and calculations, and questioning the accuracy of the equipment used.
Expert witnesses can also testify in court to explain the complexities of blood sample analysis to a judge or jury. They can present their findings clearly and understandably, using visual aids and other tools to help the court understand the scientific principles involved.
In some cases, expert witnesses may be able to identify errors or inconsistencies in the blood sample analysis that could raise doubts about the accuracy of the results. For example, they may discover that the equipment used to analyze the sample was improperly calibrated or that there was contamination during the process.
Challenging Blood Test Results in DUI Cases
Several strategies can be used to challenge the results and potentially get the charges reduced or dismissed.
One strategy is to challenge the chain of custody of the blood sample. This refers to the process of collecting, storing, and transporting the specimen from the time it is taken until it is analyzed. Gaps or inconsistencies in the process can cast doubt on the accuracy of the results. For example, if the blood sample was not properly labeled or stored, it could have been contaminated or altered, leading to inaccurate results.
Another strategy is to challenge the accuracy of the analysis. This can involve questioning the qualifications and expertise of the lab technicians who conducted the test and the reliability of the equipment and methods used. For example, if the lab equipment was not properly calibrated, it could produce inaccurate results.
The consequences of a positive blood test result can be severe. Depending on the circumstances, a conviction could lead to fines, license suspension, probation, or even jail time. Additionally, a DUI conviction can have long-lasting effects on a person's personal and professional life, including increased insurance rates, difficulty finding employment, and damage to their reputation.
Reach Out to Our Firm Today
Challenging blood test results can be an effective defense strategy. Individuals facing DUI charges should seek the help of a criminal defense attorney who can help them navigate the legal process, understand their rights, and build a strong case. Their lawyer can also assist in questioning the validity of blood test results and potentially get their charges reduced or dismissed.
To speak with one of our Naples attorneys, contact the Law Offices of Cavanaugh & Cavanaugh, P.A. at (239) 309-2006.