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Opinion Testimony in a DUI Case under Daubert

In DUI, the prosecution centers around the observations and opinions of law enforcement officers. The opinion testimony of law enforcement is crucial in defending misdemeanor DUI cases in county court. At trial, the prosecutor will ask the officer about “clues of impairment” observed during the performance of field sobriety exercises.


Your criminal defense attorney must also have experience filing and litigating Daubert motions and other types of motions to exclude this opinion testimony. 

The attorneys at Meltzer & Bell in Fort Lauderdale, FL, are experienced in filing and litigating motions to suppress and exclude evidence in a trial for driving under the influence in Broward Count, FL. We work hard to put our clients in the best position to fight for the “not guilty” verdict at trial.

Filing and litigating pre-file motions property also leads to better pre-trial negotiations if the client decides to resolve the case before trial. Either way, the attorney needs to know how to exclude prejudicial and irrelevant opinion testimony about the ultimate issue in the case – whether the person accused was impaired by drugs or alcohol.  

When the Daubert Standard Applies to Testimony in a DUI Case

Whether this testimony is admissible at trial depends on the Daubert standard. The Daubert standard requires the trial court to act as a gatekeeper by making a pre-trial determination about whether the witness is qualified to testify about the matter in dispute. The judge must also determine whether the witness based his or her opinion on sufficient facts or data that were correctly applied to reliable principals and methods.

A criminal defense attorney can file a “Daubert” motion that seeks to exclude or limit the opinion testimony by the law enforcement officer. The “Daubert” motion is filed before trial and requires an evidentiary hearing outside the presence of the jury. In most of these motion hearings, the officer will testify about his background, training, and experience relevant to rendering an opinion in a DUI or possession of marijuana case. 

On July 1, 2013, the Florida Legislature amended Florida Statutes Sec on 90.702 and codified the federal standards for determining the admissibility of expert testimony. Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993). 

Pursuant to Section 90.702, Fla. Stat. (2014): 

If scientific, technical, or other specialized knowledge will assist the trier of fact in understanding the evidence or in determining a fact in issue, a witness qualified as an expert by knowledge, skill, experience, training, or education may testify about it 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. 

Opinions that Qualify as Admissible Lay Witness Testimony

If a witness is not testifying as an expert, the witness’s testimony about what he or she perceived may be in the form of inference and opinion when: 

(1) The witness cannot readily, and with equal accuracy and adequacy, communicate what he or she has perceived to the trier of fact without testifying in terms of inferences or opinions and the witness’s use of inferences or opinions will not mislead the trier of fact to the prejudice of the objecting party; and 

(2) The opinions and inferences do not require a special knowledge, skill, experience, or training. 

In DUI cases, the criminal defense attorney can challenge the law enforcement officer’s ability to perform and testify about the defendant’s performance on HGN. In many of these cases, the trial court will consider: 

  • the officer’s training, education, and experience conducting HGN;
  • how long the officer has been conducting HGN;
  • the unique characteristics of HGN; 
  • how the officer distinguishes HGN from other forms of Nystagmus; 
  • The standardized procedures for administering HGN; 
  • Law enforcement training beginning with the academy, and including in-classroom and eld training involving HGN; 
  • If the officer is an instructor and a description of classed taught regarding HGN;
  • The number of DUI investigations and the number of times the officer performed the HGN exercise; 
  • Specialized training in conducting DUI investigations.

This article was last updated on Friday, October 28, 2016.

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