By J. Ruffin Hunt, Tampa Criminal Defense Attorney | Hunt Law | Tampa Criminal Defense | Updated October 3, 2026
What You Need to Know First
A breath or blood alcohol result is evidence, not a verdict. In Florida, the State has to show the test was done the way the Florida Department of Law Enforcement (FDLE) rules require: a certified operator, an inspected instrument, a 20-minute observation period, and two breath samples that agree within 0.020.
When those steps break down, the defense can ask the court to exclude the result or strip away the statutory presumptions that make it so powerful. Losing the number does not end every case, because the State can still try to prove impairment through driving behavior, field exercises, and video. But it often changes what the case is worth to the prosecution.
Ask most people what decides a DUI case and they will say the breath number. Blow a 0.08 or higher and the case is over. That belief is understandable, and it is wrong often enough to matter.
A blood alcohol concentration (BAC) result comes out of a process: a traffic stop, an arrest, a waiting period, a machine that needs regular inspection, and an operator who has to follow a written procedure. Every one of those steps leaves a paper or video trail. This article walks through how Florida defense lawyers test that trail, which challenges actually work in court, and which ones are mostly myths.
What Florida Law Says a BAC Result Proves
Under section 316.193, Florida Statutes, a driver commits DUI in one of two ways: by driving while their normal faculties are impaired, or by driving with a blood-alcohol level of 0.08 grams per 100 milliliters of blood, or a breath-alcohol level of 0.08 grams per 210 liters of breath. A result of 0.15 or higher triggers enhanced penalties.
Section 316.1934 then gives the State a set of presumptions. A result of 0.05 or less creates a presumption that the driver was not impaired. A result between 0.05 and 0.08 creates no presumption either way. At 0.08 or above, the result is prima facie evidence of impairment. Those presumptions are what make the number so persuasive to a jury, and they depend on the State showing that the test followed FDLE’s rules.
That last point is the foundation for almost every BAC challenge in Florida. The question is rarely “is the machine perfect?” It is “did the State do what its own rules require?”
Breath Tests: Where the Process Usually Breaks
Most Florida agencies use the Intoxilyzer 8000, and FDLE’s rules in Chapter 11D-8 of the Florida Administrative Code control how it is maintained and operated. FDLE amended parts of these rules in 2025, so the version in effect on the date of arrest is the one that matters. Defense lawyers usually focus on five areas.
1. The 20-minute observation period
Rule 11D-8.007 requires the operator or officer to reasonably ensure the person did not take anything by mouth or regurgitate for at least 20 minutes before the test. The point is to keep alcohol in the mouth from inflating the reading. In practice, this is where body-camera and jail video earn their keep. If the person was unobserved in the back of a patrol car, burped, vomited, or put something in their mouth during that window, the reliability of the result is fairly in question.
2. Two samples that have to agree
Under Rule 11D-8.002, an approved breath test means at least two samples collected within 15 minutes of each other that produce results within 0.020 g/210L. If the first two samples are further apart than that, a third must be analyzed. A single sample, or two samples that disagree without a proper third, does not meet the definition. Read the breath test affidavit line by line; mismatched times and sample counts show up more often than people expect.
3. Monthly inspections and maintenance records
Rule 11D-8.006 requires each evidentiary breath instrument to be inspected by an agency inspector at least once each calendar month, in addition to FDLE’s own inspections. Missing inspections, failed control tests, instrument error codes, repairs, or a machine pulled from service shortly after the arrest can all support a challenge. These records are part of standard discovery in a Florida DUI case.
4. Operator certification
Breath tests must be administered by an operator holding a valid FDLE permit. An expired permit at the time of the test is a straightforward problem for the State.
5. A lawful stop and arrest
Florida’s implied consent law in section 316.1932 applies to a breath test given incidental to a lawful arrest. If the traffic stop lacked a legal basis or the officer lacked probable cause to arrest, the breath result can be suppressed along with everything else that followed. Many of the strongest BAC challenges are really challenges to the stop. Our earlier guide on what to do when stopped by traffic police explains why the first few minutes of an encounter shape so much of what happens later.
Blood Tests Are Not Automatically Stronger
Blood draws are common in crash cases, when a driver cannot give breath, and in cases involving death or serious bodily injury under section 316.1933. People tend to assume a blood result is bulletproof. It isn’t. Under the FDLE rules, an approved blood test requires two portions of the same sample to agree within 0.010 g/100mL, and the sample has to be collected, labeled, preserved, and stored properly.
The Florida Supreme Court’s decision in State v. Miles, 775 So. 2d 950 (Fla. 2000), held that when the State cannot rely on adequate FDLE rules for handling blood samples, it loses the statutory presumptions of impairment, even if it gets the result admitted through the traditional scientific predicate (see this later appellate discussion applying Miles). That distinction matters. A result admitted without the presumption carries less automatic weight with a jury, and the chain of custody, storage temperature, preservative, and the draw itself all become fair ground for cross-examination.
Science-Based Defenses: What Holds Up and What Doesn’t
Some BAC defenses get repeated online far more than they succeed in court. A candid look:
- Rising BAC. Alcohol keeps absorbing for a period after the last drink. If someone drank shortly before driving, their BAC at the time of the test, often an hour or more later, may be higher than when they were behind the wheel. This defense depends on specific facts about drinking times and food, and usually needs an expert to present it.
- Mouth alcohol and reflux. Recent drinking, belching, vomiting, or gastric reflux can bring alcohol into the mouth and skew a breath reading. This is exactly what the 20-minute observation period is meant to prevent, so this argument is strongest when combined with video showing the observation period was not properly kept.
- Mouthwash, medications, and medical conditions. These come up constantly, but modern instruments include features meant to detect certain interfering substances and residual mouth alcohol. Claims based on diabetes, diets, or mouthwash need evidence, not just a possibility.
- Partition ratio arguments. In some states, lawyers argue that an individual’s breath-to-blood ratio differs from the standard used by the machine. Because Florida defines the breath offense directly in grams per 210 liters of breath, that argument does not defeat a breath-level charge in Florida, though it can still bear on whether a person was actually impaired.
Expert testimony in Florida must meet the reliability standard in section 90.702 of the Florida Evidence Code, which follows the federal Daubert approach. A toxicologist who can tie an argument to the specific test record is far more useful than one offering general doubts about breath testing.
When the Body-Camera Clock Didn’t Match the Breath Affidavit
A Hillsborough County matter handled by J. Ruffin Hunt shows how these issues come together. His client, a first-time offender, was stopped in South Tampa for drifting between lanes and later provided breath samples of 0.104 and 0.112. On paper, the case looked routine.
The breath affidavit listed a 20-minute observation period beginning at the station. The arresting officer’s body-camera footage told a different story: for much of that window, the client was alone in the back of the patrol car while the officer completed paperwork outside, and the client could be heard coughing and clearing his throat. The agency’s inspection records for the instrument were otherwise clean, so the defense focused entirely on the observation period.
Hunt filed a motion challenging the breath results on that basis. Before the hearing, the State Attorney’s Office agreed to reduce the charge to reckless driving, which allowed the client to avoid a DUI conviction and the license and insurance consequences that come with it.
Client details have been changed to protect confidentiality. The outcome of any case depends on its specific facts, and past results do not guarantee a similar outcome.
What Happens When a BAC Challenge Succeeds
A successful challenge does not always mean dismissal. It typically leads to one of these results:
- The result is excluded. If the State cannot lay a proper foundation, the jury never hears the number.
- The presumptions disappear. The result may come in, but without the instruction that 0.08 or higher is prima facie evidence of impairment.
- The case changes shape. Without a reliable number, the State must prove actual impairment through driving pattern, field sobriety exercises, statements, and video.
That last scenario is where outcomes often shift. In a DUI case that leaned heavily on a breath result, a weakened number tends to move prosecutors toward a reduced charge, such as reckless driving, or occasionally a dismissal. Where the video shows obvious impairment, though, the State may proceed on impairment alone. Honest case evaluation weighs both.
The License Case Runs on a Separate, Faster Clock
A BAC result also drives the administrative suspension handled by the Florida Department of Highway Safety and Motor Vehicles under section 322.2615. A driver generally has only 10 days from the arrest to request a formal review hearing. That hearing is also an early chance to examine the breath records and question the officer, so missing the deadline costs more than just driving privileges.
Refusing a test carries its own consequences. A first refusal leads to a one-year suspension, and a second refusal after a prior suspended license for refusal is a separate misdemeanor under section 316.1939. Knowing your rights at the time of arrest matters here, and our overview of your rights when you are arrested covers the basics.
Frequently Asked Questions
Can a breathalyzer be wrong?
Yes. Results can be affected by mouth alcohol, an observation period that was not properly kept, instrument problems, or procedural errors. The legal question in Florida is whether the test complied with FDLE rules and whether the result is reliable enough to admit.
Is a 0.08 automatically a DUI conviction in Florida?
No. A 0.08 result is strong evidence, but the State must still prove the test was valid and that the result reflects the driver’s level while driving, not just at the time of testing.
What is a motion to suppress a breath test?
It is a request asking the judge to exclude the breath result, usually because the stop or arrest was unlawful or the test did not substantially comply with FDLE rules.
Can I get FDLE maintenance records for the breath machine?
Yes. Defense lawyers routinely request inspection and maintenance records in discovery, and they often review them first.
Does a low BAC help my case?
A result of 0.05 or less creates a legal presumption that you were not impaired by alcohol. It does not prevent a charge based on other substances, but it is significant evidence in your favor.
Disclaimer
This article is general information about Florida DUI law and is not legal advice. Reading it does not create an attorney-client relationship. DUI cases depend heavily on their specific facts, the records available, and the rules in effect on the date of arrest, and Florida statutes and FDLE rules can change. If you have been arrested, speak with a licensed Florida criminal defense attorney about your own situation, and keep in mind the 10-day deadline to request a license review hearing.
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