DUI Breath Test — Intoxilyzer 8000 Defense

The Intoxilyzer 8000 is the only breath testing instrument approved for evidentiary use in Florida DUI cases — and it is the instrument Florida prosecutors rely on to prove every breath-test DUI in this state. A breath test result above .08 creates a statutory presumption of impairment under § 316.1934 — but it is a presumption the defense can rebut. Maintenance failures, calibration errors, observation period violations, and instrument limitations all create grounds to challenge the number the state is relying on to convict you.

Legally reviewed by Tonmiel Rodriguez, Board Certified Criminal Trial Lawyer — last reviewed June 2026.

What Is the Intoxilyzer 8000 and Why Does It Matter in Florida DUI Cases?

The Intoxilyzer 8000, manufactured by CMI Inc., is the only breath testing instrument approved by the Florida Department of Law Enforcement (FDLE) for evidentiary breath alcohol testing in DUI prosecutions. Under Florida Administrative Code Rule 11D-8.003, FDLE maintains an approved instruments list and the Intoxilyzer 8000 is the sole instrument on it. This matters because it means every breath test result used against a Florida DUI defendant comes from this specific machine — and every weakness in the machine, every deviation from its maintenance protocol, and every operator error is directly relevant to the reliability of that result.

What Are the Maintenance and Inspection Requirements for the Intoxilyzer 8000?

Under Florida Administrative Code Rule 11D-8.006, the Intoxilyzer 8000 must be inspected by an FDLE-certified Agency Inspector using an approved reference solution every time the instrument is used for an evidentiary test and at least every 7 days. A quarterly inspection using FDLE Form 16 must also be conducted, and the instrument must pass calibration checks within ±0.020 g/210L of the reference value. These records are public records. I request them in every breath test case. What I look for:

• FDLE Form 16 quarterly inspection reports — any failures or out-of-tolerance readings
• Agency inspection logs — all entries from 30 days before and after the defendant’s test date
• Reference solution lot numbers and expiration dates — expired solutions invalidate inspections
• Repair and maintenance logs — any service calls or parts replacements near the test date
• Instrument serial number verification — confirming the specific machine used in the defendant’s test
• Temperature control records — the instrument’s sample chamber must be at 34°C; temperature deviations cause false readings

FDLE Form 16 inspection records and agency logs often show discrepancies: late inspections, out-of-tolerance calibration checks, reference solution issues, or service calls that suggest instrument reliability problems. When these records show problems, I file a motion to suppress the breath test result or argue for jury instructions on the instrument’s unreliability.

What Is the 20-Minute Observation Period Requirement for a Breath Test?

Under FDLE Rule 11D-8.002, the administering officer must continuously observe the defendant for a minimum of 20 minutes immediately before the breath test to ensure the defendant does not eat, drink, smoke, vomit, or regurgitate during the observation period. Any of these events can introduce mouth alcohol — residual alcohol from the mouth or throat rather than deep lung air — into the breath sample, producing an artificially elevated result. The observation period is continuous and uninterrupted: if the officer left the room, turned away, was distracted by radio traffic, or otherwise lost sight of the defendant, the observation period is compromised.

I review the observation period in every breath test case. The law enforcement video recording from the DUI investigation room is the first thing I request. I look for the start time of observation, any breaks in observation, any indication the defendant burped or regurgitated (even without the officer noting it), and whether the 20-minute clock was actually running from a continuous observation or from the moment the officer stepped into the room after doing other tasks. Observation period failures are one of the most common and most effective challenges to Intoxilyzer 8000 results in the 10th Judicial Circuit.

What Is the Partition Ratio Defense in a Florida Breath Test Case?

The Intoxilyzer 8000 measures alcohol in exhaled breath and converts that measurement to an estimated blood alcohol concentration using a fixed partition ratio of 2100:1 — meaning it assumes that 2,100 milliliters of alveolar (deep lung) air contains the same amount of alcohol as 1 milliliter of blood. This ratio is a population average, not a measurement of any individual’s actual physiology. The actual partition ratio in living humans ranges from approximately 1700:1 to 2400:1, with significant individual variation. A person with a partition ratio of 1700:1 will produce a breath test reading approximately 24% higher than their actual BAC. Florida courts have recognized this documented physiological variable, and I raise it in cases where the breath test result is close to the threshold or where the clinical picture does not match the reported number.

What Is the Mouth Alcohol Defense in a Florida DUI Case?

Mouth alcohol refers to residual alcohol present in the mouth, throat, or upper respiratory tract at the time of testing — as opposed to alcohol vapor coming from deep lung air. The Intoxilyzer 8000 is designed to detect mouth alcohol through a “slope detector” that identifies the characteristic rising-then-falling pattern of mouth alcohol in the breath sample. However, the slope detector does not catch all sources of mouth alcohol and can be defeated by certain residual compounds. Sources of mouth alcohol that can produce false elevated readings include:

• Burping or regurgitation during or just before the observation period
• Acid reflux / GERD (gastroesophageal reflux disease)
• Dental work — dental adhesives, bridges, caps, and appliances can trap alcohol
• Blood in the mouth from injury or dental bleeding
• Residual mouthwash containing alcohol
• Certain medications — inhaled bronchodilators and some oral medications can affect readings

The 20-minute observation period requirement exists specifically to reduce mouth alcohol contamination. When the observation period is flawed, the mouth alcohol risk is not mitigated, and both defenses apply simultaneously — the observation period failure and the potential mouth alcohol source.

What Is the Operator Certification Requirement for Breath Testing in Florida?

Under Florida Administrative Code Rule 11D-8.005, only a person holding a valid FDLE Breath Test Operator permit may administer an evidentiary breath test. The permit requires FDLE-certified training and must be renewed. In every breath test case, I verify: (1) the administering officer held a valid, current permit on the date of the test; (2) the officer followed all testing procedures; and (3) there was no permit lapse or suspension. An expired or invalid operator permit at the time of the test means the result was obtained by an unqualified operator — a basis to suppress or exclude the result.

How Is a Breath Test DUI Case Different From a Refusal Case?

A breath test DUI gives the state a specific BAC number — and that number creates a statutory presumption of impairment under § 316.1934 that the defense must actively rebut. A DUI refusal case gives the state no number, but allows the state to argue the refusal itself is consciousness of guilt. In a breath test case, the defense attacks the reliability of the number through the calibration records, observation period, operator certification, partition ratio, and mouth alcohol. Without a chemical result, a refusal defense turns instead on the strength of the state’s impairment evidence. The two cases call for different strategies, and neither is automatically easier to defend than the other.

Related DUI Defense Pages

• DUI Defense in Florida — Complete Overview
• First DUI in Florida — Penalties and Defense
• DUI Refusal — Refusing the Breath Test (Trenton’s Law)
• DUI Blood Test Defense — Florida
• Field Sobriety Test Defense — Florida DUI
• Second DUI in Florida — Enhanced Penalties
• Criminal Defense — Polk County

Frequently Asked Questions — DUI Breath Test and Intoxilyzer 8000

Can a breath test result be challenged in a Florida DUI case?

Yes. Under Florida Administrative Code Rule 11D-8.006, the Intoxilyzer 8000 must be inspected on a regular schedule, operated by a certified permit holder, and administered following strict protocol including a 20-minute continuous observation period. Failures in any of these requirements — documented through FDLE Form 16 inspection records, maintenance logs, and video review — provide grounds to suppress the result or argue its unreliability to a jury.

What is FDLE Form 16 and why does it matter in a DUI case?

FDLE Form 16 is the quarterly inspection record for the Intoxilyzer 8000 that documents calibration checks, reference solution verification, and instrument performance. Under Florida Administrative Code Rule 11D-8.006, these inspections must be conducted at least quarterly and must demonstrate the instrument is reading within ±0.020 g/210L of the reference value. A Form 16 showing an out-of-tolerance reading, an expired reference solution, or a missed inspection near the defendant’s test date is direct evidence of instrument unreliability.

What is the 20-minute observation period for a breath test?

Under FDLE Rule 11D-8.002, the officer must continuously observe the defendant for 20 minutes before administering the breath test to prevent mouth alcohol contamination. “Continuous” means uninterrupted — any gap, distraction, or departure from observation restarts or voids the observation period. If the 20-minute clock was not properly run, the test result is vulnerable to suppression or exclusion.

What is the partition ratio and how does it affect breath test accuracy?

The Intoxilyzer 8000 uses a fixed 2100:1 partition ratio to convert breath alcohol to an estimated BAC. The actual partition ratio varies across individuals from approximately 1700:1 to 2400:1. A person with a lower-than-average ratio will produce an inflated breath test reading. This is a documented physiological defense recognized by Florida courts, particularly effective in cases where the breath result is near .08 or where the clinical picture of the defendant does not match the reported BAC level.

Can acid reflux or GERD affect a breath test result?

Yes. Gastroesophageal reflux disease (GERD) and acid reflux can cause stomach contents — including alcohol vapors — to enter the esophagus and mouth during the observation period or during the test itself, producing a falsely elevated reading. This is a recognized mouth alcohol defense. Combined with an observation period failure, it can be a strong basis to challenge the breath test result. If the defendant has a documented history of GERD, I obtain medical records and present this defense at trial or in pretrial motions.

The Intoxilyzer 8000: Florida’s Breath Testing Instrument

Florida uses the CMI Intoxilyzer 8000 as its approved evidentiary breath testing instrument under Florida Administrative Code Rule 11D-8. Every breath test result used against a DUI defendant in Florida — in Polk, Highlands, or Hardee County — was produced by this machine. Understanding how it works and how it fails is essential to defending breath test evidence.

The Intoxilyzer 8000 uses infrared spectrophotometry to measure ethanol concentration in a breath sample. The subject blows into the machine for a minimum of 3–4 seconds with sufficient pressure and volume. The machine analyzes the infrared absorption of the breath sample at multiple wavelengths and calculates a blood alcohol equivalent based on a 2100:1 partition ratio — that is, the machine assumes your blood contains 2,100 times the alcohol concentration of your breath. The result is reported as a breath alcohol level (BrAC), not a blood alcohol level (BAC), though the numbers are treated as equivalent in Florida courts.

The Florida Department of Law Enforcement (FDLE) Alcohol Testing Program is responsible for regulating, approving, and overseeing all breath test instruments in Florida. FDLE maintains the approval list, requires annual agency inspection of each instrument, and requires that the instrument be operated by a licensed breath test operator and inspected by a licensed inspector. These requirements are not optional — they are preconditions for admissibility.

The 20-Minute Observation Period

One of the most frequently litigated requirements in Florida breath testing is the 20-minute pre-test observation period. Florida Administrative Code Rule 11D-8.002 requires that the breath test operator continuously observe the subject for 20 minutes immediately prior to administering the breath test. The purpose is to ensure the subject does not belch, burp, vomit, regurgitate, or introduce any foreign substance into the mouth that could contaminate the breath sample with residual mouth alcohol.

Residual mouth alcohol is a serious accuracy problem. If you burp or regurgitate immediately before blowing into the Intoxilyzer 8000, alcohol from your stomach vapor enters the mouth and contaminates the breath sample — artificially inflating the reading. The machine cannot distinguish between deep-lung air (which should reflect blood alcohol concentration) and mouth alcohol from a recent belch. The 20-minute observation period is supposed to prevent this. If the observation period was not continuous — if the officer left the room, looked away for an extended period, was processing paperwork, or the video shows gaps in observation — the observation period is compromised and the breath result is challengeable.

In my experience in the 10th Circuit, observation period violations are more common than prosecutors admit. I pull the jail video or DUI processing video for every breath test case. I look for: the officer leaving the room, the officer standing behind the subject where mouth activity cannot be observed, the subject being left alone, or the subject having any oral activity including coughing, burping, or using a breath freshener. Any of these is a motion to suppress argument.

Mouth Alcohol and the Partition Ratio Variability Defense

Beyond the observation period, two additional scientific defenses attack the reliability of Intoxilyzer 8000 results.

The mouth alcohol defense arises when residual alcohol is present in the oral cavity at the time of the test, regardless of whether the observation period was followed. Mouth alcohol sources include: recent alcohol consumption (within the last 20 minutes), belching or regurgitation from acid reflux or GERD, dental appliances that trap alcohol, and certain mouthwashes. A person with chronic acid reflux who burps silently — without any outwardly observable signs — can have significant mouth alcohol contamination even after a clean observation period. The Intoxilyzer 8000 has a “slope detector” designed to catch mouth alcohol contamination by measuring the rate of change of the alcohol reading during the blow. But the slope detector does not catch all contamination, and its reliability has been challenged in Florida and other jurisdictions.

The partition ratio defense attacks the foundational assumption of the test itself. The 2100:1 partition ratio — the assumption that blood contains 2,100 times the alcohol of an equal volume of breath — is a population average. Individual partition ratios vary significantly: the scientific literature shows a range from approximately 1700:1 to 2400:1 in the human population. A person with a partition ratio of 1700:1 (meaning their breath has proportionally more alcohol relative to blood than average) will have their BrAC overstated by the machine when compared to their actual BAC. For a person blowing 0.09, a partition ratio of 1700 instead of 2100 means their actual BAC could be as low as 0.073 — below the legal limit. This is established physiology, documented in peer-reviewed forensic toxicology literature.

FDLE Maintenance Records and Instrument Inspection

Every Intoxilyzer 8000 in Florida must be inspected at minimum once every six months by a licensed breath test inspector under Florida Administrative Code Rule 11D-8.006. The inspection involves running the machine through a series of accuracy checks using simulator solutions of known ethanol concentration. The results are recorded in a Breath Test Instrument Inspection Report and submitted to FDLE. These records are public documents — and I request them in every breath test case.

What I look for in inspection records: any failed inspection, any inspection result outside the acceptable tolerance range (±5% of the simulator target value), any repair or replacement of components, any period of time when the instrument was out of service, and any consecutive inspections showing a pattern of drift toward overreporting. I also check whether the inspections were performed within the required intervals — a machine that was not inspected on schedule has a broken chain of regulatory compliance that goes to admissibility.

The agency’s breath test records also include the actual test record for your specific test: the internal diagnostic results printed by the machine at the time of your test. These diagnostic fields include the simulator solution temperature reading, the blank air readings, and the results from both of your breath samples. I review all of them. A simulator temperature outside the required range, a blank air reading that shows contamination, or a significant difference between your two breath samples are all grounds for challenging the result’s reliability.