Is There a Defense to My Florida DUI if I Blew Over the Legal Limit of .08 BAC?

When a person blows over the legal blood alcohol content (BAC) limit of .08, a common question they ask following a DUI stop is if their case is defensible. It is important to know that the breath or blood alcohol test is administered after the driving occurs, perhaps more than an hour later. But the State must prove your breath or blood alcohol limit at the time you were driving. To understand what defenses may be applicable in your case, it is important to understand there are two ways in which the State of Florida can attempt to prove you are guilty of DUI.

Elements Required to Prove a DUI Crime

Pursuant to Florida Statute § 316.193(1), to prove the crime of DUI, the State must prove the following two elements beyond a reasonable doubt:

  1. The Defendant drove or was in actual physical control of a vehicle.
  2. While driving or in actual physical control of the vehicle, the Defendant:
    • was under the influence of [alcoholic beverages] [a chemical substance] [a controlled substance] to the extent that [his] [her] normal faculties were impaired; or
    • had a [blood] [breath]-alcohol level of .08 or more grams of alcohol per [100 milliliters of blood] [210 liters of breath].

What Is Retrograde Extrapolation?

In certain cases, a scientific process known as “retrograde extrapolation” may be beneficial to your DUI defense. Retrograde extrapolation is used to estimate what a person’s blood alcohol content (BAC) was at a specific time based on test results taken at a later point in time.

Retrograde extrapolation considers several factors that affect how a person’s body absorbs alcohol. This allows a toxicologist to estimate a person’s BAC at the time of driving, rather than the BAC reading that may have been taken over an hour after driving. Each of the factors below affects the time it takes for a person’s body to absorb and eliminate alcohol, impacting their BAC at the time they were driving.

Examples include but are not limited to:

  • gender
  • weight
  • body mass index
  • age
  • food and alcohol consumption (when, what type, and how much)
  • alcohol tolerance

To understand the concept of retrograde extrapolation, it is important to consider how experts analyze the way alcohol metabolizes in our bodies. Experts use what is known today as the blood alcohol curve, which represents the rise and fall of a person’s BAC as their body absorbs and eliminates alcohol. After they drink alcohol, it is absorbed into a person’s body and bloodstream. The concentration of alcohol in their blood gradually rises until they reach a peak. This is commonly referred to as the absorption or rising phase of the metabolizing process. After they reach the peak, the concentration of alcohol begins to decline as the liver removes the alcohol from a person’s blood. This is known as the elimination or falling phase.

In your Florida DUI case, both the State and your defense attorney may attempt to introduce expert testimony regarding retrograde extrapolation that estimates your BAC at the time of driving.

How Retrograde Extrapolation Can Help Your DUI Defense

In certain cases, expert testimony on retrograde extrapolation can help argue that your BAC was below the legal limit at the time of driving. Through analyzing data and facts specific to your case, an expert may determine that your BAC was below the legal limit while you were driving, despite getting a reading above the legal limit of .08 BAC sometime after you were driving.

In other words, the scientific data may support an argument that your body was in the absorption phase during the time between driving and submitting a breath sample. Thus, this can help show that your BAC level was higher when the sample was taken rather than when you were driving.

To evaluate the strength of your DUI case, you should consider that the State can also use the principle of retrograde extrapolation when arguing that your BAC was above a .08 at the time of driving. To do so, the state often argues that a BAC slightly below the legal limit does not reflect the BAC at the time of driving. In that case, the State may present expert testimony that your body was in the elimination phase of alcohol metabolism when the sample was given, meaning your BAC was actually above the legal limit of .08 at the time of driving.

McNulty Parker Law, PLLC Can Defend Your DUI Charges

The science of retrograde extrapolation can be used by either the State or defense, therefore a detailed and thorough analysis of your case and its variables can help determine whether this principle is beneficial to your DUI defense. While retrograde extrapolation can be a valuable tool in combating a DUI charge involving a BAC above .08, retrograde extrapolation is not applicable in every DUI case.

If you have been arrested for DUI, you need an experienced attorney who is willing to put their knowledge to work for you. As such, contact McNulty Parker Law, PLLC online or by calling (727) 826-7135 today!

The content in this blog is for general information purposes only and should not be taken as legal advice for any individual case or situation. This blog content is not intended to create, and receipt or viewing does not constitute, an attorney-client relationship.

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The information on this website is for general information purposes only. Nothing on this site should be taken as legal advice for any individual case or situation. This information is not intended to create, and receipt or viewing does not constitute, an attorney-client relationship.