Breaking Down Chemical Test Defenses in DUI Cases

In Florida, breath and blood test evidence is often conclusive proof of intoxication. Often, but certainly not always.

That’s primarily because the Sunshine State has a per se law. Defendants with a BAC above the legal threshold are intoxicated as a matter of law. But the per se law only applies if the breath or blood test produced flawless results. As we all know, no gadget, no matter how sophisticated, is flawless.

Breathalyzers are, by far, the most common DUI chemical tests in Hillsborough County. Breathalyzers are also, by far, the most unreliable chemical tests.

So, although successfully challenging chemical test results is an uphill climb, a good Tampa criminal defense lawyer never raises the white flag in these situations. Instead, an attorney challenges the state’s evidence, forcing prosecutors to prove every element of DUI, including intoxication, beyond any reasonable doubt. This aggressive stance usually produces results that exceed your expectations.

Breath Test Issues

Florida’s updated per se law cuts off one of the primary defenses for a Tampa DUI lawyer, which was breath/blood conversion ratios. Nevertheless, some effective defenses remain, chiefly particle recognition and device reliability.

The BAC proportion is the number of ethanol (alcohol) particles in every 210 milliliters of breath. Ketone and alcohol particles are chemically similar. Both are essentially double-bonded carbon atoms. This similarity has assumed new significance in recent years, with the rising popularity of ketone diets and ketone drinks.

Many Breathalyzers, especially older models, cannot distinguish between ketone and alcohol products. So, without analyzing a breath sample beyond particle content, it’s impossible to tell if a legal or illegal substance was responsible for the positive test.

This additional analysis is impossible. Breathalyzers immediately flush breath samples after initial testing, ending all possibility of retesting or additional analysis. So, police Breathalyzer techs can only speculate as to particle analysis.

Particle analysis is a complex defense. So, a Tampa criminal defense lawyer may partner with a chemist or other expert who has the authority to explain these things to jurors and does not talk down to them.

Breathalyzer calibration is a more pressing issue as well, given the number of DUI stops and arrests in Hillsborough County. To establish device reliability, the state must prove the:

• Gadget was working at 100 percent efficiency at the time of use,
• Administering officer was fully and currently qualified to use the device,
• Device’s maintenance record was 100 percent complete, and
• Department pulled Breathalyzers that failed test one, two, or three.

The state must prove each point beyond any reasonable doubt. That’s the highest standard of evidence in the law.

Calibration isn’t just an idle academic exercise. Recently, a Massachusetts judge threw out over 10,000 breath samples due to issues with device calibration.

Blood Test Issues

Blood tests are much more scientifically reliable than breath tests. For this reason, blood test defenses often focus on the results as opposed to the process.

Search warrant adequacy is one example. Usually, officers must have valid search warrants based on probable cause, which is usually poor performance on DUI field tests, before they perform blood tests. Chain of custody is another example. Most blood samples must travel from the defendant’s body to a hospital or clinic storage area to an analysis area to an evidence locker to a courtroom. Any gap in the chain of custody casts doubt on the sample’s authenticity.

Connect With a Dedicated Hillsborough County Attorney

An adverse chemical test result doesn’t guarantee a DUI conviction. For a confidential consultation with an experienced Tampa criminal defense lawyer, contact the OA Law Firm. Convenient payment plans are available.

Source:

leg.state.fl.us/statutes/index.cfm?App_mode=Display_Statute&URL=0300-0399/0316/Sections/0316.193.html