An Attorney Explains: What To Know About Sobriety, Blood And Breath Tests In San Diego
If a driver is pulled over on suspicion of drunk driving, the police officer will likely administer a field sobriety test (FST). The officer will look for any signs that may indicate the driver has been drinking or using drugs, such as slurred speech, bloodshot eyes or the smell of alcohol. They may even look for open containers of alcohol. After observing the driver’s behavior and performance during the field sobriety test, the officer may place the driver under arrest for driving under the influence (DUI).
Our founder, attorney Mark Deniz, is a seasoned prosecutor. He graduated from La Pier’s rigorous DWI detection and standardized field sobriety testing course; he also is certified in Standardized Field Sobriety Tests under NHTSA (National Highway Traffic Safety Administration).
Examples Of DUI Field Sobriety Tests
- Standing on one leg
- Being required to walk and then turn around
- The horizontal gaze nystagmus test (HGN)
- Putting your feet together and being required to perform a backward head tip
- Correctly identifying the number of fingers a police officer holds up
- Recite backwards the entire alphabet or portions of the alphabet
- Counting backward
- Touch your nose with your finger
If you were pulled over for DUI and submitted to a field sobriety test, contact an experienced DUI attorney today. There may be a reasonable explanation for failed field sobriety tests other than impairment.
The Impact of FST Results
Field sobriety tests can have a significant impact on a driver’s case and possibly determine whether that person will face charges. The prosecution will be likely arguing that the “totality” of the evidence establishes impairment. In some cases, the FST results may be the primary basis for the prosecution in establishing an individual is impaired for purposes of driving.
It is vital you hire an experienced attorney to provide a quality defense.
Blood And Breath Tests For DUI Chemical Test
Breath and blood tests are an important part of any DUI case. After a driver is arrested for suspected drunk driving, law enforcement will request that he or she take a breath test or blood test to determine the presence of alcohol and/or drugs in the driver’s system. Please note the preliminary alcohol screening device (PAS) is NOT a chemical test in a DUI. If these occur, you need to contact our firm to speak with attorney Mark Deniz as soon as possible at 858-429-9982.
Defenses To Breath Tests And Blood Tests
Challenging breath test (also referred to as the breathalyzer) or blood test results will be a necessary part of almost all San Diego DUI cases. Here at The Law Offices of Mark Deniz APLC, our attorneys know how to evaluate all aspects of your case and of your chemical testing to determine precisely how to challenge your test results.

Examples Of Potential Defenses Used To Challenge A Breath Or Blood Test
- The test was not administered properly.
- The person who administered the test was not trained or qualified.
- The breath test device was not properly calibrated.
- The driver was not observed for 15 minutes prior to the breath test to ensure he or she did not belch or regurgitate.
- The blood sample was not mixed or handled properly.
- There was a mistake made when testing the blood sample.
Additionally, there are certain factors, which may bring into question the accuracy of a breath test, such as the driver’s weight, physical conditions or food that was eaten to challenge the test. Furthermore, the science of DUI is always evolving. Attorney Deniz is a member of the California DUI Lawyers Association, National College for DUI Defense, as well as several other organizations. He attended the prestigious National DUI college at Harvard Law School. He keeps abreast of every new viable defense that can be raised. Finally, he was a prosecutor dealing with these issues from the other side. These are key points to consider that an experienced attorney like Mark Deniz can help you with if you are faced with a DUI.
For more information regarding the history of field sobriety tests and the accuracy of them, click here.
Contact The Law Offices of Mark Deniz APLC now for a free case evaluation at 858-429-9982.