Most Common and Best Defenses to a DUI Charge
Fourth Amendment Violations
Law enforcement cannot stop your vehicle (i.e., detain you) without probable cause. Law enforcement often goes on fishing expeditions and pull people over simply because they're out late at night, or leaving the parking lot of a bar. Perhaps you were stopped at a DUI Checkpoint that wasn't operating properly. Further, blood tests and breath tests are often administered without a warrant, and without free and voluntary consent. These all amount to Fourth Amendment violations and can result in a successful defense of a DUI charge.
Make sure you DUI Attorney understands the constitutional law aspect of DUI cases. They're important.
You Weren't Driving!
Any DUI charge requires proof that the accused was actually driving. Duh! However, people who were never actually observed driving by law enforcement are routinely charged with DUI. A "no driving" defense is one of the oldest and best defenses a DUI attorney can make to a DUI charge.
Breath Test Inaccuracy
The general public may regard breath test results as generally accurate. However, these machines, like any other machine, are subject to error. These machines often go without calibration, malfunction when improperly trained officers administer them, and can be thrown off by mouth alcohol.
Title 17 of the California Code of Regulations governs the administration of breath tests. Law enforcement is required to follow these regulations in administering breath tests. Law Enforcement may fail to comply with Title 17, which can bring the results of any breath test into question.
For instance, Title 17 requires that an officer observe a subject for 15 continuous minutes prior to administering a breath test, during which time the subject should not drink, smoke, eat, or put anything in their mouth. I have had cases where officers fail to follow this practice, and have administered breath tests with chewing tobacco in subject's mouths, administered a test right after someone spit out gum, which all can effect the result of the breath test.
Rising Blood Alcohol DUI Defense
Alcohol takes approximately one to three hours to absorb into your system.
If you finish drinking and immediately get in your car for a short drive, and an officer pulls you over, then arrests you and takes you to the police station for a DUI chemical test, your blood alcohol was still rising at the time you were arrested, the chemical test results will show a higher BAC than the one you had when you were actually driving.
Your BAC at the time of your blood or breath test is irrelevant--what is relevant is what your BAC was at the time you drove. An understanding of the concept of rising blood alcohol can form the basis of a defense to DUI charges.
DUI Blood Test Errors
Blood fermentation, improper storage of a blood sample, and blood contamination can all lead to inaccuracies in a chemical blood test. Your DUI attorney can have your blood sample retested and determine through forensic toxicology whether your blood sample was properly taken and stored.
No Impaired Driving
Driving under the influence means you are incapable of driving a car with the care and caution of a sober person. If you were not driving poorly, or you driving can be attributed to some other factor, then you were not driving under the influence.