33 Fla. L. Weekly Supp. 87a: Why Your DUI Case in Florida Might Be Saved by Challenging BAC Extrapolation
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Court blocks unqualified deputy from guessing BAC—discover how Williams may help your Florida DUI defense.
📘 33 Fla. L. Weekly Supp. 87a: What Every Florida Driver Charged With DUI Should Know
Online Reference: FLWSUPP 3302NWIL
Case Summary: In State of Florida v. Nykea Williams, a Miami-Dade judge ruled that a sheriff’s deputy without formal scientific training could not testify about a driver’s BAC at the time of alleged intoxicated driving, using retrograde extrapolation from a delayed breath test result.
Hey there—if you’ve been charged with a DUI in Florida, this might be a game-changer
Facing DUI charges can feel overwhelming—suddenly, everything seems on the line: your reputation, freedom, insurance, and future. One key piece of evidence prosecutors rely on is retrograde extrapolation—estimating your BAC at the time you were driving using a breath or blood test taken later, often with gaps that can span 30 minutes or more.
But State v. Williams shines a spotlight on an important legal safeguard: Florida courts will block unqualified experts from speculating about your BAC. This case is your leverage—read on to find out how this ruling could benefit your defense, what to look for in your case, and how DUI2GO can help you take control.
What State v. Williams Means for Your Defense 🚗
In April 2025, Nykea Williams was pulled over at 3:52 AM. Ninety minutes later, she submitted a breath test with a BAC of .065. The prosecution planned to argue that her BAC at the time of driving was over the legal limit—based solely on a math formula applied by Deputy Closius.
But here’s what happened at the hearing:
- Deputy Closius lacked any formal training in toxicology, pharmacology, lab science, or medicine.
- He admitted he didn’t know Williams’s weight, sex, metabolism, drinking habits, or meal timing—all crucial data that can significantly impact blood alcohol readings.
- His testimony rested only on a generic formula he’d learned in DUI training—not on scientific precision.
The judge concluded that this was insufficient under Daubert standards (Fla. Stat. § 90.702). Therefore, Closius was prevented from testifying about Williams’s BAC at the time of driving.
Why This Ruling Could Be a Lifeline for You
- It highlights the unreliability of gap-time extrapolations. BAC shifts depending on many personal factors—without solid evidence, it’s speculative.
- It empowers you to challenge unqualified witnesses. Many prosecution witnesses rely on DUI formulas without real scientific credentials.
- It shifts momentum toward your defense. Pretrial motions based on Williams can force evidence suppression or even case dismissal.
Q&A: Your Top 10 Questions, Answered Clearly and Fully
Retrograde extrapolation uses a later BAC result (like .065) and a standard elimination rate (around .015–.020 per hour) to estimate BAC at the time of driving. It seems straightforward, but it ignores essential variables—like your body weight, how much food you ate, metabolism, and how fast you drank. These unknowns can massively skew the estimate. In Williams, the court recognized this, and said you can’t guess your BAC without real scientific grounding.
Yes—but only if they’re truly trained in science, not just DUI protocol. To stand up under Daubert, the expert needs credentials like toxicology certification, lab experience, peer-reviewed publications, or advanced coursework. Regular DUI training doesn’t cut it.
Florida follows the Daubert standard (see Fla. Stat. § 90.702), which requires scientific testimony to be (1) reliable, (2) validly based on data, and (3) relevant. The judge acts as a “gatekeeper” to keep out opinion testimony that fails these criteria—like what happened in Williams.
Important questions:
When was the test taken compared to the stop?
Does the report record your weight, last drink, any food eaten?
Does the officer have credentials in toxicology or science?
If records are missing or the officer is unqualified, it strengthens your motion to exclude.
Yes, but it depends. If the time between driving and testing is wide, and the officer extrapolates without real science backing, Williams says you can challenge them. Breath test alone doesn’t prove BAC at the time of driving.
The average elimination rate is between 0.015 and 0.020 BAC per hour. But your personal rate can be much slower or even faster depending on your physiology, food, liver function, and other factors. That’s why a one-size-fits-all formula isn’t reliable in court. Our online breath test factors in this variable.
It involves documenting that:
The witness lacks scientific qualifications.
They ignored basic variables.
The method is inherently unreliable or misapplied.
We request an evidentiary hearing and ask the judge to block the expert from testifying.
Yes. Cases like Vitiello (5th DCA 2019) have excluded retrograde extrapolation when experts ignored key facts. Williams added weight by challenging a trained deputy directly under Daubert’s stricter standard.
We specialize in:
Reviewing your officer’s qualifications and BAC timeline.
Identifying gaps in records or protocols.
Crafting and filing expertly researched Daubert motions.
Engaging credible forensic toxicologists to support your defense.
Without expert testimony, the prosecution may lack proof of intoxication at driving time. This can lead to charges being reduced or dropped—or at minimum, give leverage to negotiate better plea terms.
What You Can Do Now: Friendly, Practical Steps
- 📅 Set up a free case call.
We’ll analyze your arrest report, breath test timing, and officer credentials. - 🗂️ Preserve your records.
Collect all your DUI documents—the arrest report, device calibration logs, medical notes, and officer training history. - ⚖️ File a well-crafted Daubert motion.
We’ll prepare the legal arguments needed to challenge expert testimony. - 🧑🔬 Secure a qualified toxicologist.
We work with experts who can testify with scientific rigor—unlike a deputy without a lab background.
About DUI2GO
At DUI2GO, we’re led by experienced DUI defense attorneys and toxicology specialists who fight every day for drivers just like you. We’re committed to:
- Personalized strategy tailored to your case.
- Cutting-edge legal research and expert support.
- Transparent communication and advocacy at every stage.
📞 Call us today at (813) 222-2220 for your free consultation.
📍 Prefer to meet or call online? Email us or book a session on our Contact Page.
Friendly Final Word
If you’re charged with DUI in Florida and your BAC was near the limit—or tested late—the Williams decision could give your defense a major boost. Don’t leave your case up to chance. Talk to us today—we’re on your side, ready to uncover the truth behind the numbers.
📞 (813) 222-2220
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— The DUI2GO Defense Team
The complete text of the courts decision is below:
33 Fla. L. Weekly Supp. 87aOnline Reference: FLWSUPP 3302NWILCriminal law — Driving under influence — Evidence — Expert — Blood alcohol content — Extrapolation — Deputy who has no formal toxicology, medical, biomedical, or pharmacological training is not qualified to testify as to what defendant’s blood alcohol level would have been at time she was driving based on results of breath test performed one and a half hours after she was detained
STATE OF FLORIDA, Plaintiff, v. NYKEA WILLIAMS, Defendant. County Court, 11th Judicial Circuit in and for Miami-Dade County. Case No. ADH25QE. April 17, 2025. Marcus Bach Armas, Judge. Counsel: Maria Paula Molano, Miami, for Plaintiff. Emma Sheridan and Sean Werkheiser, Miami, for Defendant.ORDER GRANTING MOTIONTO EXCLUDE EXPERT TESTIMONY
THIS CAUSE came before the Court on Defendant’s Motion to Exclude Expert Testimony (the “Motion”). The Motion seeks to exclude the testimony of Miami-Dade Sherriff’s Office Deputy R. Closius (“Closius”), who the State designated as an expert witness to offer an opinion as to what the Defendant’s blood alcohol content (“BAC”) would have been at the time she was driving given her BAC breath test result of .065 g/100mL approximately 1.5 hours after she was detained.1 The Court has carefully considered the Motion, the State’s response, the scientific literature, the testimony of the proffered expert, the very capable oral argument of the parties, and the law. For the reasons set forth herein, the Court concludes that Deputy Closius is not qualified to testify as an expert regarding retrograde extrapolation. Therefore, the Motion is granted and the proffered expert may not testify at trial regarding his opinion of the Defendant’s blood alcohol levels.
I. BACKGROUND
At 3:52 am on the date of incident, Nykea Williams (“Defendant”) was detained in connection with a driving under the influence (“DUI”) investigation. After performing field sobriety exercises, she voluntarily provided a breath test which generated a blood alcohol result of .065 g/100mL. Ms. Williams was charged with driving under the influence. In advance of trial proceedings, the State designated Deputy Closius as an expert to testify regarding the science underlying metabolization rates of alcohol by the human body, and more specifically, to offer an expert opinion as to what the Defendant’s BAC would have been at the time she was driving given her BAC breath test result of .065 g/100mL approximately 1.5 hours after she was detained. Defendant then filed the Motion seeking to exclude the proffered expert testimony pursuant to Fla. Stat. § 90.702 and Daubert v. Merrell Dow Pharm., Inc., 509 U.S. 579 (1993), arguing that Deputy Closius is not qualified to testify competently regarding such matters. The State filed a response opposing the Motion, and an evidentiary hearing was held on April 16, 2025 during which testimony was taken from Deputy Closius.
II. LEGAL STANDARD
“For nearly a century, Florida followed the Frye standard for admissibility of expert testimony. However, on June 4, 2013, Florida Governor Rick Scott signed into law House Bill 7015, amending Florida Statute section 90.702, and transforming Florida into a Daubert jurisdiction. After a number of failed attempts, Florida lawmakers finally succeeded in aligning Florida’s standards for expert admissibility with the standards that govern in federal court and many states around the country.” Erica W. Rutner & Lara B. Bach, Florida’s “Brave New World”: The Transition from Frye to Daubert Will Transform the Playing-Field for Litigants in Medical Causation Cases, 20 Barry L. Rev. (2015). While the Florida Supreme Court initially rejected the Legislature’s efforts as an unconstitutional infringement on the judiciary’s rule-making authority, it later changed course and formally adopted Daubert in 2019. See In re Amendments to Florida Evidence Code, 278 So. 3d 551 (Fla. 2019) [44 Fla. L. Weekly S170a].
As a result, section 90.702 of the Florida Statutes now governs the admissibility of expert testimony in Florida courts. The statute provides:
If scientific, technical, or other specialized knowledge will assist the trier of fact to understand the evidence or to determine a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education, may testify thereto in the form of an opinion or otherwise, if: (1) the testimony is based upon sufficient facts or data, (2) the testimony is the product of reliable principles and methods, and (3) the witness has applied the principles and methods reliably to the facts of the case.
Because the statute was intended to mirror Federal Rule of Evidence 702, see Fla. Stat. §90.702 (Pmbl. 2013) (expressly adopting Daubert and its progeny in stating the statute’s purpose of eliminating pure opinion testimony), federal case law on the subject, which has been developed over the course of many decades by the federal courts (including the United Supreme Court), is both instructive and highly persuasive.
Daubert requires district courts to undertake a rigorous analysis and ensure “that an expert’s testimony both rests on a reliable foundation and is relevant to the task at hand.” Daubert, 509 U.S. at 597. Courts applying Daubert principles refer to the trial court as the “gatekeeper” in this context because “when engaging in a Daubert analysis, the judge’s role is that of evidentiary ‘gatekeeper,’ that is, the one who determines whether the expert’s testimony meets the Daubert test. The purpose of the gatekeeping requirement is to ensure an expert employs in the court[ ]room the same level of intellectual rigor that characterizes the practice of an expert in the relevant field.” State v. Barber, 360 So. 3d 1180, 1185 (Fla. 2nd DCA 2023) [48 Fla. L. Weekly D785b] (internal citations and quotations omitted) (emphasis added).
“This function inherently requires the trial court to conduct an exacting analysis of the foundations of expert opinions to ensure they meet the standards for admissibility under Rule 702.” United States v. Frazier, 387 F.3d 1244, 1260 (11th Cir. 2004) [17 Fla. L. Weekly Fed. C1132a]. In determining the admissibility of expert testimony, the trial courts are required to conduct a three-part inquiry about whether: (1) the expert is qualified to testify competently regarding the matters they intend to address; (2) the methodology by which the expert reaches their conclusions is sufficiently reliable as determined by the sort of inquiry mandated in Daubert; and (3) the testimony assists the trier of fact, through the applications of scientific, technical, or specialized expertise, to understand the evidence or to determine a fact in issue. Hendrix ex rel. G.P. v. Evenflo Co., 609 F.3d 1183, 1194 (11th Cir. 2010) [22 Fla. L. Weekly Fed. C1025a] (citing Frazier, 387 F.3d at 1260). The burden is on the proponent of the expert testimony to show, by a preponderance of the evidence, that the testimony satisfies each prong. See id. (citing Boca Raton Cmty. Hosp., Inc. v. Tenet Health Care, 582 F.3d 1227, 1232 (11th Cir. 2009) [22 Fla. L. Weekly Fed. C130a]).
In this case, only the first prong is at issue. In other words, the question for the Court is straightforward: is Deputy Closius qualified to testify as an expert regarding retrograde extrapolation and render a reliable opinion as to what the Defendant’s blood alcohol level would have been at the time she was driving?
III. FINDINGS OF FACT AND CONCLUSIONS OF LAW
1. Deputy Closius is an officer with decades of experience in law enforcement that has conducted numerous DUI investigations, breath tests, and blood draws.
2. Deputy Closius has attended a multitude of conferences and workshops and been extensively trained on matters pertaining to DUI investigations, including metabolization rates of alcohol by the human body, as well as mathematical formulas that can be used to conduct a retrograde extrapolation analysis.
3. Deputy Closius has no knowledge of the Defendant’s drinking habits, underlying medical conditions, prescription medications, race/ethnicity, body composition, volume of distribution, or biological sex, all of which are factors that could have a substantial impact on alcohol metabolization rates in the context of a retrograde extrapolation analysis.
4. To the contrary, Deputy Closius was “flying blind” as to these individual factors, notwithstanding his acknowledgment that these factors could significantly affect retrograde extrapolation results.
5. Instead, Deputy Closius’ proffered expert opinion is based solely on (1) the results of the breath test, (2) the time elapsed between initial detention and the breath test, (3) when Defendant stopped eating and/or drinking, and (4) a mathematical formula developed by toxicologists that he is familiar and applied to the case at hand.
6. Deputy Closius is not a toxicologist and has received no formal toxicology training, although he noted at the hearing that he spends a lot of with toxicologists in the field.
7. Deputy Closius has no formal medical training.
8. Deputy Cloisus has no formal biochemical or pharmacological training.
9. Deputy Closius has never authored or edited a peer-reviewed publication regarding metabolization rates or retrograde extrapolation.
10. Deputy Closius has never received lab training.
11. Deputy Closius does not and has never taught or lectured regarding the specific biological principles underlying the metabolization rates of alcohol in the human body.
12. Deputy Closius is capable of utilizing mathematical formulas and applying best practices provided by toxicologists for use in the field, but when asked to explain why these best practices and formulas have evolved over the years, Deputy Closius was unable to do so, conceding that he did not possess technical the expertise required to explain the changes in best practices governing retrograde extrapolation.
13. Deputy Closius is able to perform elementary retrograde extrapolation analyses using the “easiest method,” but does not have the expertise to perform a more advanced analysis that would account and adjust for potentially and materially impactful factors that are unique to each human being (e.g., height, weight, race, liver function, drinking habits, medical history, etc.).
14. The State has presented no case law — whether binding or persuasive — supporting the proposition that a police officer with no formal toxicology, medical, biochemical, or pharmacological training can be qualified as an expert under Daubert and offer an expert opinion as to what a defendant’s BAC would have been at a specific point in time prior to a blood alcohol test.
15. Despite diligent search, the Court was also unable to find any such case law. To the contrary, retrograde extrapolation cases in Florida all appear to involve challenges to the retrograde extrapolation testimony of witnesses specifically trained in the field of toxicology. See, e.g., Vitiello v. State, 281 So.3d 554 (Fla. 5th DCA 2019) [44 Fla. L. Weekly D2480e]; State v. Barber, 360 So. 3d at 1185.
16. Of course, the qualification of an expert witness is to be evaluated by trial courts on a case-by-case basis, and this Court is not expressly or impliedly suggesting the existence of a bright-line rule establishing that a police officer cannot be qualified as an expert witness on retrograde extrapolation. In fact, authority from outside the State of Florida has concluded that a former police officer, who later became a field technician analyst who was extensively trained and co-authored publications in the fields of pharmacology, pharmacokinetics, and blood alcohol physiology, can pass muster under Daubert and testify as an expert on retrograde extrapolation. State v. Turbyfill, 243 N.C. App. 183 (2015).
17. The instant case, however, presents us with a very different set of facts. While Deputy Closius has vast experience with DUI investigations and is well-versed on blood draws, the effects of alcohol on the human body, and the best practices and formulas developed by the trained scientists (e.g., toxicologists and pharmacologists) that study retrograde extrapolation, his testimony made clear to the Court that he does not possess a sufficient technical understanding of the scientific principles underlying same and thus would not be able to “employ[ ] in the court[ ]room the same level of intellectual rigor that characterizes the practice of an expert in [retrograde extrapolation].” Barber, 360 So. 3d at 1185.
18. Because the State has failed to meet its burden to show by a preponderance of the evidence that Deputy Closius is qualified to testify competently regarding the highly technical science of retrograde extrapolation, the Motion must be granted and Deputy Closius may not testify at trial.
IV. CONCLUSION
For the reasons set forth above, the Defendant’s Motion is GRANTED and Deputy Closius shall not testify as a qualified expert witness in the above-captioned matter.
__________________
1As explained by the Fifth District Court of Appeal in Vitiello v. State: “[r]etrograde extrapolation applies a mathematical calculation to estimate a person’s blood alcohol level at a particular point in time by working backward from the time the blood [sample] was taken. Hence, the need for retrograde extrapolation arises when a test puts a suspect’s BAC below the legal limit, but the State seeks to prove the suspect was above the legal limit at the time he or she was operating a car or boat. The alcohol metabolization process consists of three phases: absorption, peak blood alcohol level, and elimination. The absorption phase begins immediately upon consumption. Once consumed, some alcohol is absorbed through the lining of the stomach into the bloodstream. The rest passes to the small intestine where it is absorbed into the blood and carried throughout the body. During the absorption phase, a person’s blood alcohol level increases until all the alcohol is absorbed into the blood. Once absorption is complete, the person’s blood alcohol level peaks and begins to decline. How long it takes to reach peak alcohol level can vary depending on factors, including the subject’s drinking pattern, time of last drink, and when the subject last ate.” 281 So.3d 554 (5th DCA 2019) [44 Fla. L. Weekly D2480e] (internal citations and quotations omitted).* * *