All About DUI Evidence
If you have been accused of driving under the influence of alcohol or drugs, you probably have a lot of questions. I am here to help. I am drunk driving attorney Peter M. Liss and I have over 30 years of experience fighting DUI charges, including DUIs involving car accidents, juvenile DUIs, felony DUIs and DUIs involving commercial licenses. One of the most important factors in a driving under the influence case is the DUI evidence against the defendant. Because drunk driving charges are based upon such unique evidence, you should only work with a lawyer experienced in fighting these specific charges.
Chemical Test Results: Breathalyzer Vs. Blood Test
Chemical analysis of a person’s blood or breath is the cornerstone of the prosecution’s case. These may include blood, breath and, in very rare and limited circumstances, urine tests that have been administered by trained professionals. Chemical Blood Alcohol Concentration (BAC) analysis is designed to evaluate whether or not you have a BAC above the legal limit (0.08% for most adults, 0.01% for minors and 0.04% for commercial drivers) or if you were under the influence of drugs.
Under California’s Implied Consent law, you are legally required to submit to a chemical test if probable cause exists for your arrest. Failure to do so will result in a search warrant being obtained to draw blood and you still will be charged with drunk driving. Violating the Implied consent law will also cause you to lose your driver’s license for a full year and you will face mandatory jail time if you are convicted.
While officers will often ask those they suspect to be driving under the influence of alcohol to take a breath test without informing them that they also have the option to take a blood test, you have the right to choose either of the chemical tests. Drivers who have been accused of driving under the influence of drugs generally must take a blood test, though a urine test may be an option in some rare circumstances. Your attorney may be able to challenge the evidence no matter which chemical test you take, but here is what you should know about each option:
Breathalyzers Are Less Accurate
Breath tests, which are performed through the use of breathalyzer machines, are the best known and most frequently used type of evidence in a DUI case. In fact, many people do not know they have an alternate choice at all. But despite its regular usage, this test is not known for being entirely accurate. In fact, there are many things that can throw off the results (though not sucking on pennies or batteries like you hear in so many myths on beating the breathalyzer) and these factors almost always fool the breathalyzer into thinking your Blood Alcohol Content (BAC) is higher than it actually is include:
- Chemicals in the testing area
- Diet sodas
- Hand sanitizer
- Improper calibration
- Inexperienced operators
- Low-carb diets
- Regurgitation, including burping or vomiting, within a 15 minutes of taking the test
For all these reasons, you should write down everything that happened before and after you took the breathalyzer so if something gave you an artificially high result, drunk driving attorneys can challenge it. This is particularly true if your BAC test result is just over the legal limit.
While there are many things that can make breathalyzer results artificially high and make it possible to challenge this evidence, the down side is that breathalyzers do not provide a stored sample for future retesting, which blood tests do. As a result, if you believe you are genuinely not under the influence, having a blood sample can often be beneficial because if a they come back positive, your lawyer can retest the sample and may get different results than the original test.
Blood Tests Can be Retested for Accuracy
Blood tests are much more accurate in general than breath tests. That might make the results more difficult to challenge, but if you are certain you are not over the legal limit, it might make the blood test a preferable option because the sample can be retested. These tests also take a while longer to administer in most cases, so your BAC may decrease while you wait to be tested, although if you drank a lot immediately before you drove, you could actually test higher because your body has had time to metabolize the alcohol -the premise behind the rising alcohol defense.
While it can be harder to fight the results of a blood test, the benefit is that your sample will be stored so your lawyers can have it retested if there is any question about the accuracy of the results. In fact, if the results of your test of the sample are lower than the official police results, this could actually benefit your case.
Additionally, while fewer things can cause a blood test to go wrong compared to a breath test, there are a number of procedures that must be strictly adhered to for a result to be considered legally admissible as DUI evidence. This includes proper collection, storage, transportation, and testing methods, for example:
- an alcohol swab was used to clean the skin before taking a sample
- the sample was stored improperly
- the test isn’t performed properly
- the sample was tampered with
- the wrong type of tube was used
- those tasked with moving the blood lost track of it at any time
All of these factors should be looked at in careful detail by your lawyer. Courts may throw out the evidence if your lawyer can prove it has been tampered with, not properly collected, misplaced somewhere during the chain of custody or improperly stored.
Field Sobriety Tests as DUI Evidence in San Diego
You’ve probably seen field sobriety tests portrayed a thousand times in movies and TV shows when the cop asks a suspect to stand on one leg and touch their nose, to walk in a straight line heel to toe, or to recite the alphabet backwards. But in reality, there are only three legitimate field sobriety tests that can be used as evidence in a drunk driving case. While these three examinations are considered the most accurate of all field sobriety tests, that’s not actually saying much, since the results are still largely subjective on the part of the police officer and can be drastically less accurate outside of a laboratory setting. This is why these exams are entirely optional. Unfortunately, most people don’t know this and police officers rarely inform suspects that they have the right to abstain. Luckily, an experienced DUI lawyer can fight the results of these tests.
The Three Standard Field Sobriety Tests
The three standardized field sobriety tests (FST) that have been approved by the National Highway Traffic Safety Administration for on-the-field use by law enforcement are: the walk and turn test, the one leg stand and the horizontal gaze nystagmus. These tests are all intended to evaluate the suspect’s ability to follow directions, but each individual field sobriety test measures additional factors as well. Taken together, the National Highway Traffic Safety Association considers these tests to be anywhere from 82-91% accurate depending on which study is cited. That means even under ideal circumstances, one driver out of ten could be falsely identified as being under the influence.
In the real world, where roads are uneven, freeway traffic is distracting, test-takers are nervous that their future could depend on the outcome of these tests, and rain, wind or particularly hot or cold weather can make test-takers uncomfortable, the accuracy of these sobriety tests drops significantly. In fact, many sober individuals do not pass field sobriety tests. To make matters worse, by the time an officer asks someone to take these tests, they have generally already decided that the suspect is intoxicated through the use of a drug or alcohol, so the officer’s judgment is far from unbiased.
While your lawyer can always challenge the results of these tests, he will have even more reason to challenge the evidence if he can show that the road was in poor condition, there was heavy traffic, you suffer from a medical condition, you had improper footwear, there were poor weather conditions at the time of the test or any other reason why the test could have been performed improperly.
The Walk and Turn Test (WAT)
The walk and turn test requires a suspect to walk heel to toe in a straight line and then turn and walk back. This test helps officers evaluate someone’s balance and their ability to remember and execute a simple set of instructions. This test has an accuracy of between 68-79%, again depending on which study is cited, but uneven pavement, physical handicaps, memory conditions and poor footwear can result in a sober person easily failing this test.
The One Leg Stand (OLS)
The one leg stand, as its name implies, requires the test subject to stand on one leg. While doing this, the suspect must then count out loud. This tests measures a person’s ability to balance while focusing on a simple activity. The NHTSA claims this test is anywhere from 65-79% accurate. Like the walk and turn test, poor footwear and mental or physical impairments can negatively affect a person’s likelihood of passing this test.
The Horizontal Gaze Nystagmus (HGN)
The last test, the horizontal gaze nystagmus, has a strange name, but it merely requires a person to follow a pen or flashlight with his or her eyes. In this test, officers look to see if the person’s eyes move smoothly or erratically. The NHTSA claims this test to be the most accurate, with an accuracy rate of 77-89%. But many eyesight problems will make a person fail the horizontal gaze nystagmus test every time.
As if that weren’t bad enough, a scientific study taking a deeper look at the accuracy of the test said it is deeply flawed at its core and called the NHTSA’s continued use of the HGN a “deliberate fraud.” It’s not just the design of the test either, but the way it is performed. In fact researchers found that 95% of police officers administer the test improperly.
Other Field Sobriety Tests
Other tests, including the nose-touch test and the ability to recite the alphabet backwards, have been proven by the NHTSA itself to be scientifically inaccurate when evaluating a person’s intoxication levels. Nevertheless, many officers still ask suspects to perform these tests and then attempt to use the defendant’s results as evidence of his or her guilt. While it is possible to dispute the results of most field sobriety tests (especially if you have any kind of mental or physical impairment), the results of these tests have no scientific basis and are particularly easy to challenge.
Officer DUI Observation Testimony
The police officer’s testimony is one of the most key pieces of evidence in a drunk driving trial and can make or break your case. That’s because the officer will explain why he or she pulled you over and what made him or her believe you were drunk. He will also describe your behavior and list any statements you made before and after your arrest.While the courts trust the memory of a police officer far more than a civilian, they also accept that police are human and do make mistakes, which is why a dashboard cam or conflicting officer testimonies can work to your advantage.
Your DUI lawyer may also question details of the officer’s testimony. For example, officers often claim a suspect smelled like alcohol, but the reality is that he or she is usually only smelling the kind of alcohol the defendant was drinking, not pure alcohol. This means that if you spilled wine on your shirt or were drinking a particularly pungent variety of gin, the officer easily could have smelled it, even if you were entirely sober by the time you drove. The police may also point out that you had bloodshot eyes, something which can easily be explained away by exposure to cigarette smoke (a common occurrence at parties or outside of bars), a medical condition, or fatigue.
And, of course, if the officer violated your rights in any way, this could result in some of the evidence against you being withheld from the criminal trial or even in the charges being dropped altogether if the violations were serious enough. One of the most common reasons for these charges to be dropped is because police did not have reasonable suspicion to stop you.
As you can see, the three main types of DUI evidence used in trials can all be challenged as long as you work with the right attorney. As a graduate of UC Berkeley Law School with over 30 years of experience defending people just like you fight these charges, I can help you if you have been accused of driving under the influence of alcohol or drugs. For more information on the types of evidence used in a DUI criminal case, please call (760) 643-4050 to schedule a free initial consultation in my office located just across the street from the Vista courthouse and jail. I offer reasonable rates and accept all major credit cards.
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