Understanding DUI Blood Testing Errors and How a Florida DUI Defense Attorney Can Challenge the Results

As a Florida DUI Defense Attorney, I've seen firsthand how critical DUI blood test results can be in determining the outcome of a case. But just because the state claims your blood alcohol concentration (BAC) was above the legal limit does not mean the test was accurate, valid, or admissible in court. The truth is, DUI blood tests in Florida are not infallible. There are numerous reasons why the results might be wrong, and I've helped many clients get charges dismissed or significantly reduced by attacking these very flaws.

What the Law Says About DUI Blood Testing in Florida

Under Florida Statute §316.1932(1)(a), any person who operates a motor vehicle in the state is deemed to have given consent to a test of their blood, breath, or urine if lawfully arrested for an offense allegedly committed while under the influence of alcohol or drugs.

However, blood testing is not used as the standard method. Instead, it's typically administered under specific conditions laid out in §316.1932(1)(c):

"A blood test may be administered only if a breath or urine test is impractical or impossible, or if the person is unconscious or otherwise incapable of refusing."

Additionally, Florida Statute §316.1933(1)(a) allows law enforcement to require a blood test without consent when a person is involved in a crash involving death or serious bodily injury and there is probable cause to believe the driver was impaired.

So, while blood testing is permitted, the process is governed by strict legal and procedural safeguards. If the state does not follow those procedures to the letter, the test results may be thrown out.

Common Problems With DUI Blood Test Accuracy

As a private attorney who handles DUI defense throughout Florida, I know that DUI blood tests can go wrong in a number of ways. These are not rare technicalities, but real problems I've seen in court repeatedly.

Contamination and Improper Storage

Blood samples must be drawn, labeled, transported, and stored according to established protocols. If the sample is not refrigerated, is exposed to bacteria, or is not sealed properly, fermentation can occur inside the vial. That process can cause the blood alcohol level to rise artificially, making it appear that you were more intoxicated than you actually were.

Chain of Custody Issues

The chain of custody is the documented trail that shows who handled the blood sample at each stage. If the state cannot prove exactly when and by whom the sample was drawn, stored, and tested, the accuracy of the results becomes highly questionable. Even one break in the chain of custody can cast enough doubt to exclude the results from evidence.

Lack of Proper Qualifications

Under Florida law, only licensed medical professionals may draw blood for DUI testing. If an unqualified person drew the sample, it's not just a technical mistake. It's a legal reason to have the results excluded.

Improper Alcohol Swabs

Medical personnel are not supposed to use alcohol-based swabs to clean the area where the needle is inserted, but it happens. That mistake can introduce alcohol into the sample itself, skewing the results and giving prosecutors false ammunition.

Defenses I Use As A Florida DUI Defense Attorney To Challenge Blood Test Results

When you hire me to defend your DUI case, I leave no stone unturned in scrutinizing the blood test process. These are a few defenses I regularly raise to fight DUI blood evidence.

Illegal Blood Draw

If the police did not follow the law regarding when and how they can draw your blood, that alone could be enough to suppress the evidence. I've won cases by proving that my client never gave proper consent and the situation did not fall within the exceptions that allow a warrantless blood draw.

Fourth Amendment Violations

Florida DUI blood tests are still subject to constitutional protections against unreasonable searches and seizures. In many cases, police fail to obtain a warrant or fail to meet the exceptions that justify skipping that step. If your rights were violated, the blood test results may not be used against you.

Analytical Error or Lab Mistake

Labs are run by humans, and humans make mistakes. From equipment calibration issues to sample mix-ups to misinterpreting toxicology results, there are many ways a lab can get it wrong. I frequently request full lab documentation and records to expose inconsistencies or violations of standard testing protocol.

Rising Blood Alcohol

Even if the blood test was performed correctly, I can argue that your BAC was actually below the legal limit while you were driving, and it only rose afterward. Alcohol takes time to be absorbed into the bloodstream. If there was a significant delay between the time of driving and the blood draw, this defense can be particularly effective.

Why You Need a Private Florida DUI Defense Attorney

The public defender's office is often overworked and underfunded. While they may be qualified, they rarely have the time to conduct an in-depth investigation into the testing procedures used in your case. As a private attorney, I give your case the individual attention it needs.

I work directly with toxicologists, subpoena hospital or lab records, depose officers and technicians, and meticulously review every step taken from the moment of arrest to the filing of charges. That's what it takes to beat DUI blood test evidence in Florida.

Real Case Example: BAC Suppressed Due to Chain of Custody Error

One of my clients was involved in a single-car accident in Hillsborough County. Police claimed he smelled of alcohol and was slurring his speech, but he was dazed from the crash. They took him to the hospital and ordered a blood draw.

The lab later reported a BAC of 0.19—more than twice the legal limit. But when I subpoenaed the records and deposition of the lab tech, I found that the sample had been left unrefrigerated for over 10 hours and that the sample had been signed out by someone who was not listed on the chain of custody form.

I filed a motion to suppress the blood test evidence. The court granted the motion. Without the BAC evidence, the prosecutor dropped the DUI charge to a reckless driving civil citation. My client avoided jail, saved his license, and walked away with a fine instead of a criminal record.

What Happens If You Don't Challenge the Blood Test

If you don't fight the results, the court will almost certainly treat the BAC level as accurate and admissible. A BAC of 0.08 or higher can lead to:

  • Jail time
  • Thousands in fines
  • Mandatory license suspension
  • Ignition interlock installation
  • DUI school and alcohol counseling
  • Long-term insurance rate increases
  • A permanent criminal record

If your BAC is 0.15 or higher, or if you have a prior DUI conviction, the penalties increase significantly. You could be facing a felony DUI, especially if there was a crash, injury, or child in the vehicle.

Florida Statutes Related to DUI Blood Tests

Let me quote some relevant sections of Florida law so you can understand what the state relies on.

Florida Statute §316.1932(1)(a):

"Any person who accepts the privilege of operating a motor vehicle within this state is, by operating such vehicle, deemed to have given his or her consent to submit to an approved chemical test or physical test…"

Florida Statute §316.1933(1)(a):

"If a law enforcement officer has probable cause to believe that a motor vehicle driven by or in the actual physical control of a person under the influence of alcoholic beverages…has caused the death or serious bodily injury of a human being, a law enforcement officer shall require the person to submit to a test of the person's blood…"

These are powerful tools for law enforcement, but they only apply if the requirements are strictly met. If they aren't, I can fight the charges—and win.

Florida DUI Defense Frequently Asked Questions

Can I refuse a DUI blood test in Florida?

Yes, in most cases you can refuse a blood test, unless you are unconscious or involved in a crash involving serious injury or death. However, refusal can result in an automatic license suspension under Florida's implied consent law. That said, if the police did not follow proper procedures, I may be able to challenge both the test and the refusal penalty.

How long does it take to get DUI blood test results in Florida?

It depends on the lab backlog, but results can take anywhere from a few weeks to a few months. I use that time to begin investigating your case, gathering bodycam footage, and requesting lab protocols so we're ready to challenge the results the moment they're released.

Can DUI blood test results be wrong?

Absolutely. Contamination, improper storage, fermentation, lab errors, or even alcohol-based skin swabs can skew results. I've had many DUI cases reduced or dismissed by proving these exact issues.

Do I need a lawyer if I failed a blood test?

Yes, more than ever. A failed blood test is not the end of the road. A private DUI defense lawyer can challenge the legality of the blood draw, the chain of custody, lab reliability, and how the BAC results were interpreted. A public defender often lacks the time or resources to mount that kind of challenge.

What happens if my DUI blood test is thrown out?

If I successfully suppress the blood test evidence, the prosecution may have no scientific evidence of impairment. This weakens their case significantly and often leads to a dismissal, reduction to a non-DUI offense, or favorable plea terms that avoid jail and license suspension.

Call Our Florida DUI Defense Attorney Today for Help With Your Case

If you or someone you love is facing DUI charges based on a blood test, do not assume the results are accurate. I will fight for you. As a Florida DUI Defense Attorney, I've successfully challenged DUI blood evidence across the state and helped clients keep their licenses, their freedom, and their clean records.

Contact Musca Law 24/7/365 at 1-888-484-5057 For Your FREE Consultation

Musca Law, P.A. has a team of experienced criminal defense attorneys dedicated to defending people charged with a criminal or traffic offense. We are available 24/7/365 at 1-888-484-5057 for your FREE consultation. We have 35 office locations throughout the state of Florida and serve all counties in Florida, including Jacksonville, Miami, Tampa, Orlando, St. Petersburg, Hialeah, Port St. Lucie, Cape Coral, Tallahassee, Fort Lauderdale, the Florida Panhandle, and every county in Florida.