What is Probable Cause for a DUI in Florida?

When a police officer stops a motorist because of either a driving infraction or for other “reasonable” grounds, the officer will not yet have “probable cause” to arrest the person for DUI. The law requires that the officer have more information than merely bad driving.  


To arrest someone for DUI in Florida, the law requires the police officer to have  


“reasonably trustworthy information’ sufficient to cause a person of reasonable caution to believe that the driver is under the influence of alcoholic beverages [or chemical substance] to the extent that the driver’s normal faculties are impaired or the driver’s blood or breath alcohol level is .08 or higher.”i  


In the same case in which the Florida courts stated the standard for probable cause needed for a DUI arrest, the concurring judge’s opinion quoted the Black’s Law Dictionary’s definition of probable cause: 


“Probable cause. Reasonable cause; having more evidence for than against. A reasonable ground for belief in the existence of facts warranting the proceedings complained of. An apparent state of facts found to exist upon reasonable inquiry (that is, such inquiry as the given case renders convenient and proper), which would induce a reasonably intelligent and prudent man to believe, in a criminal case, that the accused person had committed the crime charged, Cook v. Singer Sewing Mach. Co., 138 Cal.App. 418, 32 P.2d 430, 431.” 


What Evidence Gives Police Probable Cause to Arrest You for DUI? 


How does an officer go from only having “reasonable suspicion” that justifies pulling a motorist over to have “probable cause” to arrest them for DUI? The Florida courts have made clear that the answer to that question will vary with the facts of each case.  


In some cases, a driver’s manner of driving can be a factor in building probable cause. A single failure to use a turn signal or performing a “rolling stop” at a stop sign instead of coming to a complete stop, are grounds for police to stop a motorist. But they are hardly indicative of an impaired driver without more evidence. 


However, some driving behavior can be “consistent” with an impaired driver: 


  • weaving or zig-zagging across the lanes 
  • just missing an object, another vehicle, or a curb 
  • stopping for no reason 
  • sudden stopping or acceleration 
  • driving at night without headlights 
  • driving much slower than traffic 
  • straddling the center of the road 
  • veering into an oncoming traffic lane 


Even though these behaviors may trigger someone to suspect a driver is under the influence, they are still not enough by themselves to constitute probable cause to make a DUI arrest.  


Learn More> Debunked: Florida DUI Myths & Facts 


Determining a Driver Is Impaired 


When the police approach a driver, they pull over, they immediately observe the driver’s appearance, physical movements, speech pattern, their responsiveness to questions and directions. If they observe any of the following indications of a driver’s impaired normal faculties, they gain additional building blocks of probable cause to make a DUI arrest: 


  • slurred speech 
  • disheveled clothing 
  • odor of alcohol, especially on a driver’s breath 
  • red and/or watery eyes 
  • repeating questions and/or answers  
  • confusion 
  • clumsy fine motor skills (dropping ID or other documents) 
  • admitting to drinking alcohol 


If the officer observes these characteristics when they have personal contact with the driver, they can reasonably suspect the driver is impaired, but from what?  


The mere smell of alcohol on a driver’s breath, without more, is NOT probable cause to make a DUI arrest.  


If “looking at the totality of circumstances,” a reasonably cautious person would believe the driver was under the influence of alcohol or drugs, then the officer could have probable cause to make a DUI arrest. But, without more, the case against the driver is not a sure win for the prosecutor. 


Field Sobriety Tests as Evidence of Alcohol-Related Impairment 


The Standardized Field Sobriety Tests (SFSTs) most people are familiar with from seeing them in the media, including the “One Leg Stand,” the “Walk and Turn,” and the “Horizontal Gaze Nystagmus” (HGN) tests. We won’t go into the details of each SFST in this blog post, but we will explain how they were developed and what value they have for the officer in determining probable cause to arrest a driver for DUI. 


Before Field Sobriety Tests were developed, the court had only the police officer’s reported observations and opinion based on experience to decide if the office had probable cause to arrest a suspected drunk driver. In 1975, the National Highway Traffic Safety Administration (NHTSA) started researching the chemical reaction of alcohol on the brain and identifying how consuming different amounts of alcohol would affect a test subject’s ability to perform physical exercises. 


Eventually, NHTSA produced persuasive data (not conclusive) that a person’s score from a series of field sobriety tests administered in a particular manner could predict the approximate level of alcohol content in a person’s blood or breath. When all three SFSTs were administered by police in precisely the correct way, the percentage of accurate predictions was somewhere between 65 percent and 88 percent. The frequency with which the tests identified drivers with a BAC of 0.08 or higher was impressive. 


Of course, most police officers do not administer the field sobriety tests in precisely the way they were designed, leading to a high number of inaccurate scores attributed to drivers who take the tests.  


But, courts across the country rely heavily on the officer’s reports of how the driver scored on the field sobriety tests. And because the tests are based on scientific research, many courts accept a driver’s reported failure on a field sobriety test as conclusive evidence of probable cause to make a DUI  arrest. 


Value of Body Cam and Dashboard Cam Evidence 


With the increased use of dashboard-mounted cameras and police bodycams, we no longer must rely entirely on the police officer’s testimony about how a driver performed the field sobriety tests. Instead, experienced DUI defense lawyers can review the videos recorded during the arrest and compare the driver’s performance against the officer’s report. 


DUI defense lawyers can often find that an officer administered the test incorrectly, scored it incorrectly, conducted the tests in inappropriate road conditions, or in bad weather or lighting conditions. The video also records the driver’s interaction with the officer, perhaps revealing that the officer exaggerated the degree of the driver’s confusion or slurred speech. 



Challenging Probable Cause Can Beat a Breathalyzer Reading Above 0.08 


The most compelling evidence prosecutors can present to a court to convict a defendant of DUI is a 0.08 or higher result from a well-administered breathalyzer test. Many drivers facing DUI charges in which they blew high breathalyzer scores think they have no chance of winning their case. But when experienced DUI defense lawyers get a chance to examine the many errors and unsupported conclusions the officer used as probable cause to arrest the driver, the breathalyzer results can be neutralized. 


Without sound probable cause to make the arrest, no breathalyzer results are admissible.  


Don’t throw in the towel just because you may have blown a 0.08 or higher. Contact our experienced DUI defense lawyers at Stechschulte Nell to get professional help analyzing your case. Call us at 813-280-1244.  

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