Understanding the Accuracy and Limitations of DUI Blood Tests and How an Experienced Attorney Can Make a Difference

Blood tests are often considered the most accurate method of measuring blood alcohol content (BAC) in DUI cases in Florida. However, while DUI blood tests are seen as more reliable than breath tests, they are not without flaws. The accuracy of a DUI blood test can be affected by several factors, including how the blood was collected, stored, and analyzed.

As an attorney defending clients against DUI charges, I know that blood test results can make or break a case. But these tests are not infallible, and there are ways to challenge their accuracy in court. In this article, I’ll walk you through the basics of DUI blood tests in Florida, the potential issues that can arise, and how having the right legal defense can help reduce or fight DUI charges.

How DUI Blood Tests Work in Florida

When a law enforcement officer suspects a driver of being under the influence of alcohol or drugs, they may request a chemical test to determine the driver’s level of impairment. Florida law provides for three types of chemical tests: breath, urine, and blood. Blood tests are typically used when breath tests are not feasible or when the officer suspects drug impairment.

Under Florida Statutes Section 316.1932, drivers who are arrested for DUI are deemed to have given implied consent to a blood test if there is reasonable suspicion that the driver is impaired, especially if there is an accident involving serious injury or death. However, in most routine DUI stops, a breath test is conducted unless there are specific circumstances requiring a blood test.

Blood tests are performed by taking a sample of the driver's blood, which is then sent to a laboratory for analysis. The lab measures the amount of alcohol or drugs in the blood, and this result is used as evidence in the DUI case.

Factors That Can Affect the Accuracy of a DUI Blood Test

While blood tests are generally considered more accurate than breath tests, several factors can impact the reliability of the results. If any of these issues are present, the validity of the blood test results can be questioned in court:

1. Contamination During Collection

The accuracy of a DUI blood test starts with how the blood is drawn. Blood must be collected in a sterile environment using proper procedures. If the blood sample is contaminated during the collection process, it can lead to inaccurate results. For example, using non-sterile equipment or improper sanitization of the puncture site can introduce contaminants that affect the BAC reading.

2. Improper Storage of the Blood Sample

Once the blood sample is collected, it must be stored correctly to preserve its integrity. Blood samples are typically kept in vials containing preservatives to prevent clotting and fermentation. If the sample is not properly stored, the preservatives may not work as intended, leading to fermentation in the vial. This can cause the BAC reading to be falsely elevated because the alcohol in the blood sample increases over time due to improper storage conditions.

3. Delayed Testing

Timeliness is crucial in DUI blood tests. Blood samples should be tested as soon as possible to ensure accurate results. Delays in testing can cause the sample to degrade, which can lead to inaccurate BAC readings. In some cases, a blood sample may sit for days or weeks before it is tested, which can compromise the results. This delay can also be a point of defense, as a blood alcohol level can fluctuate in the hours following the time of driving.

4. Errors in Lab Analysis

The laboratory process itself is not immune to errors. Laboratories handling DUI blood tests must follow strict protocols to ensure accurate results. However, human error, equipment malfunctions, and cross-contamination can occur, leading to faulty results. Errors in labeling, improper calibration of lab equipment, or failing to follow standard procedures can all compromise the accuracy of a blood test.

5. Medical Conditions or Medications

Certain medical conditions and medications can interfere with the accuracy of DUI blood tests. For instance, people with diabetes or acid reflux may have elevated levels of substances in their blood that mimic the presence of alcohol. This can lead to false positives in blood alcohol content readings. Similarly, medications that interact with alcohol or mimic its effects can also impact the results of the test.

How DUI Blood Test Results Are Used in Court

In Florida, the results of a DUI blood test are critical pieces of evidence for the prosecution. If the blood test shows a BAC of 0.08% or higher, this provides the legal basis for a DUI charge. In cases where drugs are involved, the blood test will indicate the presence of illegal substances or prescription medications that impair the driver’s ability to operate a vehicle.

However, just because the blood test results show a certain BAC or drug level doesn’t mean the case is over. The defense can challenge the accuracy of the results by examining the collection, storage, and testing procedures. If any errors are found, the blood test results may be deemed unreliable, and the prosecution’s case can weaken significantly.

Defenses Against DUI Blood Test Evidence

As a criminal defense attorney, my goal is to scrutinize every aspect of the blood test process to identify potential weaknesses in the prosecution’s case. There are several key defense strategies that can be used to challenge the accuracy of DUI blood tests:

1. Challenging the Chain of Custody

For blood test results to be admissible in court, the prosecution must establish a clear chain of custody. This means they must document every step the blood sample went through, from collection to testing, to ensure it wasn’t tampered with or contaminated. If there are gaps in the chain of custody or if the blood sample was mishandled, the results may be inadmissible as evidence.

2. Questioning the Timing of the Test

In DUI cases, the timing of the blood test is crucial. Blood alcohol levels can rise and fall over time, so the BAC measured hours after the alleged offense may not reflect the level at the time of driving. This phenomenon, known as retrograde extrapolation, can be used to argue that the blood test results are not an accurate reflection of the driver’s impairment at the time of the incident.

3. Medical or Health Issues

If you have a medical condition or are taking medication that could have affected the blood test results, this can be raised as a defense. Conditions like diabetes, GERD, or kidney disease, as well as certain prescription medications, can lead to inaccurate readings. An experienced attorney will work with medical experts to demonstrate how your condition or medication impacted the test results.

4. Procedural Violations

Florida law requires law enforcement officers to follow specific procedures when requesting and administering blood tests. If the police failed to follow proper protocol, such as obtaining a valid warrant or ensuring the blood draw was conducted by a qualified medical professional, the blood test results could be excluded from evidence. Additionally, if there was no reasonable suspicion for the traffic stop or DUI arrest, any evidence obtained from the blood test may be thrown out.

The Importance of Hiring an Experienced Attorney

When you’re facing DUI charges, especially those based on blood test results, it’s critical to have an experienced criminal defense attorney on your side. An attorney who understands the complexities of DUI blood testing can examine the details of your case and build a strong defense to challenge the accuracy of the test.

Here’s how hiring an experienced attorney can make a difference:

  • Knowledge of Blood Testing Procedures: A skilled attorney will know how DUI blood tests should be conducted, stored, and analyzed. They will investigate whether any errors were made in your case and use that information to challenge the prosecution’s evidence.

  • Access to Expert Witnesses: An experienced attorney will have access to medical and forensic experts who can testify about the potential flaws in the blood testing process. These experts can provide critical testimony that may cast doubt on the accuracy of the blood test results.

  • Fighting for Charge Reduction: If the evidence against you is weak, an attorney can negotiate with the prosecution to reduce the charges. This may result in a lesser offense, such as reckless driving, which carries fewer penalties and does not come with the same long-term consequences as a DUI conviction.

  • Minimizing Penalties: In cases where a full dismissal isn’t possible, an attorney can work to mitigate the penalties you face. This may include negotiating for probation instead of jail time, or securing a reduced license suspension. The goal is to protect your future by minimizing the impact of a DUI conviction.

  • Protecting Your Criminal Record: A DUI conviction can have far-reaching effects on your life, including job loss, higher insurance rates, and difficulty obtaining housing. By fighting the charges or negotiating a favorable plea deal, an attorney can help protect your criminal record and reduce the long-term consequences of a DUI conviction.

Call to Action

If you or someone you know is facing DUI charges based on blood test results, it’s essential to take action quickly. These tests are not infallible, and with the right defense, you can challenge the accuracy of the evidence against you. Contact Musca Law 24/7/365 at 1-888-484-5057 for your FREE consultation. Musca Law, P.A. has a team of experienced Florida criminal defense attorneys dedicated to defending people charged in Florida with a criminal or traffic offense. They serve all 67 counties in Florida and are available 24/7/365 at 1-888-484-5057 for your FREE consultation.

Florida DUI Blood Test FAQs

How reliable are DUI blood tests compared to breath tests?

DUI blood tests are generally considered more accurate than breath tests because they directly measure the amount of alcohol or drugs in the bloodstream. However, blood tests can still be subject to errors due to improper collection, storage, or lab analysis. A skilled attorney can investigate whether any of these issues apply to your case.

Can I refuse a DUI blood test in Florida?

Yes, you can refuse a DUI blood test in Florida, but there are consequences. Under Florida’s implied consent law, refusing a blood test can result in an automatic license suspension. Additionally, if you are involved in an accident causing serious injury or death, law enforcement may be able to compel a blood test without your consent.

What is the chain of custody, and why is it important in DUI blood test cases?

The chain of custody refers to the documentation of every step that a blood sample goes through, from collection to analysis. It ensures that the sample wasn’t tampered with or contaminated. If the prosecution can’t establish a clear chain of custody, the blood test results may be excluded from evidence.

How long do blood alcohol levels stay elevated after drinking?

Blood alcohol levels typically peak about 30 to 90 minutes after drinking, depending on several factors like the amount consumed, body weight, and whether you’ve eaten. After that, the BAC starts to decrease. This is important in DUI cases because the blood test results may not accurately reflect your BAC at the time you were driving.

Can DUI blood test results be wrong if I have a medical condition?

Yes, certain medical conditions like diabetes or acid reflux can affect blood test results, leading to false positives or elevated BAC readings. If you have a medical condition that may have influenced your blood test, an attorney can work with medical experts to challenge the results.