The Fourth District Court of Appeal has ordered a new trial for a man convicted in Broward County of two counts of vehicular homicide, holding that a detective who was not an accredited accident reconstructionist was improperly allowed to estimate the vehicles’ speeds using a “momentum formula” without the expert-testimony analysis section 90.702, Florida Statutes, requires.
At trial, Detective Michael Wiley testified to the speeds of the vehicles based on a calculation using what he called a “momentum formula.” The trial court allowed it on the theory that he was merely testifying about his investigation. According to the opinion, Wiley used vehicle weights derived from averages found through internet searches, calculated departure angles using Google Maps and a protractor, assumed the Corolla’s approach angle was zero because “[t]hat is how we are taught to do it when we use this formula,” and could no longer produce the field sketch documenting his calculations.
The Fourth District held that was error. Wiley “opined as to the vehicles’ speeds based on a formula which he apparently learned during his training,” and “[t]his is not permissible lay opinion testimony.” “Because Wiley’s calculation depended on specialized knowledge and methodology, it constituted expert opinion testimony subject to section 90.702.” The State essentially conceded error, arguing only that it was harmless, and the court left open whether momentum analysis can be reliable when properly performed.
The court also held the error was not harmless. Although the vehicles’ event data recorders supplied speed information, testimony established that the data could not be reliably interpreted without independent accident reconstruction, so Wiley’s calculations “did not merely duplicate the event-data-recorder evidence” and “purported to corroborate that evidence on an issue central to whether the defendant drove recklessly.” The court reversed the convictions and sentences and remanded for a new trial. It affirmed the use of a six-person jury and the revocation of Faustin’s probation in a related case, but vacated the probation sentence for resentencing with a corrected scoresheet.
Download the full opinion (PDF)
Citation: Faustin v. State, Nos. 4D2024-2667 & 4D2024-2669 (Fla. 4th DCA Oct. 7, 2026).
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