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DUI Breath, Blood and Urine Tests

An experienced defense lawyer can undermine the evidence against you

Tests play a significant role in DUI cases in Florida. The police use breath, blood, and sometimes urine tests to determine the level of alcohol in a suspect’s body, and prosecutors charge people with DUI on that basis.

If you failed a test, you might think your DUI conviction is a foregone conclusion, but that’s not the case at all. An experienced DUI defense attorney who knows the science behind the tests can undermine the case against you and fight to get your charges dropped or for a Not Guilty verdict at trial. Police make mistakes and do not have proper training, and there are many factors that can call a chemical test into question.

The three types of tests used in Florida DUI investigations

The most common type of test used by Florida police in DUI investigations is the breath test, and the most common breath test instrument is a device called the Intoxilyzer 8000. Police officers are allowed to request a breath test when they have reasonable cause to believe a person was driving or in physical control of a vehicle while under the influence of alcohol. The breath test uses an infrared beam to analyze your breath for ethyl alcohol particles.

Blood tests can also be used in DUI investigations under certain circumstances. Specifically, a police officer is allowed to request a blood draw when a DUI suspect appears for treatment at a medical facility and a breath or urine test cannot be practically administered, or in felony DUI or DUI manslaughter cases with a warrant. They can also obtain a blood sample with the suspect’s voluntary consent, or subpoena a blood sample when a healthcare provider takes a blood test of the suspect first and notifies police that the blood alcohol concentration is above the 0.08 legal limit. If you get a subpoena for your medical records, call immediately to fight that subpoena!

Urine tests are not often used in DUI cases, but the police can request a urine sample when a suspected drunk driver blows under the legal limit of 0.08 and the officer has evidence that the driver may be under the influence of a chemical or controlled substance. Urine tests are generally much less accurate and reliable than blood or breath tests. There is no “per se” or level of impairment in a urine case like 0.08 in a breath test case.

Florida’s implied consent law

Florida’s Implied Consent law means that if police have probable cause to believe that you are driving under the influence, they can request that you submit to a chemical test (breath or urine). If you refuse to take the test, you will automatically be given a driver’s license suspension that prevents you from driving for at least a year – unless you’re able to beat the suspension in the formal review process. Refusing a breathalyzer test can also affect your eligibility for a diversion program.

If you have a previous DUI conviction, then refusing a breath test becomes a criminal offense.

How BAC affects DUI cases in Florida

Contrary to popular belief, you aren’t necessarily convicted or acquitted of DUI in Florida based solely on the results of a breath or blood test. Ultimately, your conviction comes down to whether the jury believes your “normal faculties” were impaired. The breath or blood alcohol concentration (BAC) affects the presumption of impairment in the instructions given to the jury. For drivers age 21 or older, the presumptions work like this:

  • If the breath or blood test reading is 0.05 or less, the jury is instructed to presume that you were not under the influence to the extent your normal faculties were impaired, but the prosecution can introduce other evidence to overcome that presumption.
  • If the breath or blood test reading is 0.08 or more, the jury is instructed to presume that you were under the influence to the extent your normal faculties were impaired, but the defense can introduce other evidence to rebut that presumption.
  • If the breath or blood test reading is more than 0.05 but less than 0.08, there is no presumption one way or another. The jury can consider the BAC as well as any other evidence introduced to determine whether your normal faculties were impaired.

In short, your BAC is not the be-all end-all of your case. You can beat a DUI charge if you can convince the jury that your normal faculties were not impaired, the breath test machine was inaccurate or wrong, or that the evidence does not prove beyond a reasonable doubt that you were impaired. That’s why having a defense lawyer who knows the law, knows the science behind breath and blood tests, and knows Polk County juries is critical.

You need the right lawyer to overcome test results and beat a DUI charge

The science behind DUI tests and Field Sobriety Exercises (SFST’s) is complex, and unfortunately, police and prosecutors often use bad science to convict people of DUI and similar offenses. As one of the few Florida attorneys to have earned the Forensic Lawyer-Scientist designation, I have in-depth knowledge of specimen testing, best practices, and how to prove biological evidence unfit for trial.

Depending on the circumstances, there are numerous arguments that can be used to pick apart the testing evidence against you. For example, the Intoxilyzer 8000 actually does not specifically measure ethyl alcohol; it will show a positive reading if any organic molecule in the “methyl” group, such as acetone, methyl alcohol, diethyl ether, or acetaldehyde, is in your breath. Some of these chemicals exist naturally in the body, or they can be present because you inhaled fumes that contained them. Problems with the way the machine is maintained or calibrated can also affect test results.

Likewise, numerous mistakes can affect the reliability of DUI blood tests. Your sample may have been contaminated, switched or intermingled with someone else’s sample, or even fermented inside the vial. Problems with the chain of custody of a blood or urine sample can call the entire test into question.

Depending on the situation, your attorney may be able to file a Motion to Suppress, which if successful can get the test results thrown out. If the prosecutor doesn’t have enough other evidence for a conviction, that could result in the charges being dropped. Otherwise, your attorney’s job is to question the test results at trial. That includes both choosing jurors who will be open to those arguments during jury selection and hammering those arguments home in court.

The key is to talk to an experienced DUI defense attorney right away. Don’t assume your test results are your destiny. Get the right lawyer on your side to fight back. Call today or use the online contact form for your free consultation with Thomas C. Grajek, Attorney at Law.

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