In California, it is illegal to drive a motor vehicle if you are intoxicated with drugs or alcohol. This is because these substances affect people differently and could lead to distorted driving and accidents. You are probably asking yourself how an officer can determine if you are under the influence in violation of the law. Well, California has put legal measures that hold all motorists to similar standards. These standards rely on what is called blood alcohol concentration (BAC). If the officer measures your BAC and finds that it exceeds the standard legal limit, you may have a DUI case to answer.
However, note that you can still challenge the validity of the BAC results since they are not always accurate. To do this, you need help from an expert attorney who understands the procedure to be followed when administering BAC tests for the results to be considered valid. If arrested for DUI in San Jose, reach out to San Jose DUI Attorney Law Firm. Our attorneys will help you fight your case, not only based on BAC results, but will also bring any evidence of the prosecution under scrutiny. In this article, we help you learn more about BAC, how it is determined, and how to know if the test results are valid.
The Definition of Blood Alcohol Concentration (BAC)
BAC refers to the level of alcohol amount in someone’s bloodstream. Other people refer to blood alcohol concentration as blood alcohol level or blood alcohol content, which are legally correct. BAC is measured in the form of a percentage, e.g., 0.08%. 0.08% is the standard lawful limit that applies to most drivers in California. This percentage stands for the quantity of alcohol in grams found in every 100ml of a person’s blood.
If the percentage is higher, it indicates that the person has an increased amount of alcohol in their system. On the other hand, a lower percentage indicates the presence of less alcohol amount in the blood. A person’s blood alcohol content can be determined directly through blood testing. Or, it could be approximated through a breath test.
Drunk-driving chemical testing for blood alcohol concentration is deemed a scientifically correct way of measuring blood alcohol. Also, more crucial to note is that they are lawfully admissible as proof in a DUI prosecution.
A person’s blood-alcohol level is measured through the administration of either a breath or blood test. All these methods are deemed to be reliable if the test is administered correctly. Also, the results drawn from both of these methods are admissible in a court of law.
Drunk-Driving Breath Tests
Breath tests are the most common tests used to measure one’s blood alcohol level in California. This is because these kinds of tests provide instant results and are less invasive. In California, breath tests are categorized into two. That is:
- Preliminary alcohol screening (PAS) tests, administered before an arrest
- Post-arrest breath tests taken after a person has been arrested
How Blood Alcohol is Measured Using Breath Tests
Breath tests do not measure a person’s blood alcohol percentage directly. Instead, they measure the alcohol found deep in the lungs, where it’s nearest to the person’s blood supply. After the breathalyzer measures this alcohol, it mathematically converts the amount to an approximately equal percentage of blood alcohol. The formula used in all these is called a partition ratio.
Partition ratios differ from one person to another and also from one situation to the next. However, in California, the law places the partition ratio at 2100:1. This figure implies that the alcohol amount present in 2100ml of breath obtained from deep inside the lungs is assumed to be legally equivalent to the alcohol amount in 1ml of blood.
PAS tests are usually administered before DUI arrests are made. Generally, this occurs after a person is stopped by traffic cops or after he/she stops at a DUI checkpoint. A driver can legally refuse to take a PAS test except if he/she is under twenty-one years or he/she is on DUI probation.
Post-Arrest Breath Tests
Once you have been legally arrested for driving under the influence, you will be allowed the option of taking a blood or breath test. Note that you must take a post-arrest breath test whether you previously took the PAS test or not. Refusing to submit to this test may subject you to harsh consequences, which include an automatic driver’s license suspension for a minimum of one year and enhanced penalties.
The only advantage of refusing chemical testing, however, is that the prosecutor will have no way of proving your BAC. This may prevent prosecution for DUI. Without the BAC results, the prosecutor will only show you are guilty by determining that your driving was impaired.
Most people choose to do a breath test since it is minimally invasive. A post-arrest DUI test is the same as a preliminary alcohol screening test except for one thing; it is administered on a desktop at the hospital or police station. In certain cases, the arresting officer may conduct the post-arrest DUI breath test by the roadside. If this is the case, then it appears the same as the PAS breath test. However, the main difference to note between these two tests is that whereas PAS tests are optional, post-arrest tests are mandatory regardless of where they are given.
Drunk-Driving Blood Tests
A blood test directly measures a person’s blood alcohol. Due to this fact, blood tests are considered the most accurate tests when it comes to determining someone's BAC. However, they have to be administered as per the procedure.
In carrying out a blood test, your blood sample is taken by a person who is licensed to do so by California. The sample is then divided into two. One portion of the sample is taken to a laboratory to be analyzed. It may take several days for your attorney to get the results of this test.
The main benefit that a blood test has over a breath test is; a portion of the blood sample could be kept for later use. This means you or your attorney can be given the sample to independently test it and determine if the initial results were accurate. This is known as blood split motion.
BAC is not usually determined by urine testing in California drunk-driving cases. A urine test can detect alcohol presence in a person’s body accurately. However, it is less reliable compared to a blood or breath test when it comes to measuring the specific alcohol amount present. Therefore, urine tests are only used in DUI cases in California in case:
- Both breath and blood test are not available
- You are incapable of submitting to either a breath or blood. Reasons a person may not be able to take any of these tests may include:
- A health condition like a clotting or breathing disorder
- An exceedingly high level of unconsciousness or inebriation which makes it impossible or hard to do a breath test
The Standard Legal BAC Limit in California
As the law provides, any person who operates a motor vehicle with more than a given alcohol amount in his/ her blood system is said to be intoxicated. This is referred to as the per se drunk-driving law as outlined in the following Vehicle Codes:
- VC 21352b, operating a vehicle with a blood alcohol content of 0.08% or more. This vehicle code applies to adult non-commercial drivers.
- VC 23140, underage driving under the influence with a blood alcohol content of 0.05% or more. This statute applies to drivers that are under 21 years
- VC 23152d, commercial drunk-driving with a blood alcohol concentration of 0.04% or more. This law applies to commercial drivers.
- VC 23152e, passengers for hire drunk-driving with a blood alcohol level of 0.04% or more. This Vehicle Code applies to Uber, limo, Lyft, and taxi drivers.
Also, apart from the above laws, California has two zero tolerance statutes. Violating these laws is not technically a DUI offense. Instead, it is a civil offense, and compliance is measured through a PAS breath test. The two statutes include:
- VC 23136, the Zero Tolerance law for under 21 drivers
- VC 23154, the Zero Tolerance law for persons on probation for DUI
Per se means in itself. Certain DUI offenses qualify to be per se since having a blood alcohol level at or more than the stipulated limit is deemed as breaking the law in and of itself. In a case like this, the prosecution doesn’t need to show that you were impaired.
Drivers who are under 21 years or those on probation for DUI violate these statutes by operating a vehicle with a blood-alcohol level of 0.01% or more. In this case, these persons can face DUI charges if their BAC measures at any high, applicable level.
How Blood Alcohol Concentration is Used
Law enforcement officers use BAC at two stages: during a DUI arrest and DUI investigation. At a traffic stop, in case the police officer has reason to suspect that you are intoxicated, he/she can start a drunk-driving investigation. One of the things the officer can request you to do during the investigation is to take a preliminary alcohol screening test.
If you blow into the breathalyzer and it registers a BAC that is below the stipulated limit, the police officer usually lets you go after issuing a warning or traffic ticket. However, if the breathalyzer registers a positive result (BAC above the acceptable limit), you will probably be arrested and required to take a blood or breath test.
If your BAC is more than the legal standard limit, you may not be well-served if you take a PAS breath test. You can and maybe should politely refuse to submit to one. The police officer may still put you under arrest anyway. If your BAC is below the standard legal limit, you also have the right to refuse the test. However, most drivers prefer to submit to the test to prove to law enforcement that they aren’t drunk.
Post-arrest DUI teats are evidentiary. Evidentiary means it is admissible in court. The prosecution can use the test results as proof that you drove while drunk. Usually, you must be given the freedom to choose between a blood and breath test. However, in certain instances, the police may see it necessary to test your blood in addition to a breath test. This happens especially if the police have reason to believe you are intoxicated with drugs.
Title 17 Regulations and DUI Chemical Tests
Title 17 regulations set forth procedures to follow when administering a DUI chemical test. If all the procedures therein aren’t followed, a skilled DUI defense lawyer can contest the results in court.
How BAC is Used during Prosecution
In a drunk-driving case, the prosecuting attorney will use the results of your BAC as well as other proof to show that you were either:
- Over the standard legal limit, therefore, you are guilty as per the DUI per se law
- Impaired, thus guilty of DUI
DUI per se depends on an unbiased measurement of being impaired. If your BAC is above or at a given level, like 0.08% for adult non-commercial drivers, you are lawfully considered too intoxicated to drive. Ordinary DUI, on the other hand, is subjective. The prosecution must prove that you were unable to operate a vehicle safely because you were impaired.
BAC is only one of the elements of subjective DUI conviction. The higher your blood alcohol level, the more likely it is that you were impaired when driving. However, additional proof of being impaired is usually needed. The evidence may include:
- Evidence of when you drove
- The arresting officer’s testimony about your physical intoxication symptoms and driving pattern
- Witnesses’ testimony. This includes the passengers that were in your vehicle
There’s no easy way to tell the best test to go for between a breath and blood test. Each test has its benefits and disadvantages, and a skilled DUI attorney can also contest each test in court. Despite the teat you choose to go for, the critical thing to do is; be polite to the administrator of the test, and you should avoid saying much. Chemical test results aren’t the only proof that the prosecutor can use to convict you of DUI. The arresting officer can also testify on what you say and how you say it.
Challenging BAC Test Results
Just because blood or breath test results indicate, a certain blood alcohol level does not mean they are accurate. Generally, you can challenge these results by arguing several points. They include:
- The test administrator did not follow the proper procedure when administering the test
- The blood or breath sample was not correctly handled, and it was possibly contaminated
- The testing device wasn’t calibrated as the law requires
- The officer didn’t properly advise you of the consequences you will face if you fail to take a chemical test
- You have a health condition (like diabetes or GERD), which led to falsely high BAC results
- You were on a low-carb or high-protein diet at the time of the test
- You had residual mouth alcohol in your mouth at the time of the test
- You had rising blood alcohol during the test (meaning your BAC level was lower when you drove)
Determining Impairment When the BAC is Below .08%
Officers undergo training on how to detect the symptoms of impairment in a person apart from BAC. The first step an officer takes is to observe how you drive. If you drive erratically, it will cause the officer to pull you over. Erratic driving includes:
- Failure to keep up with the traffic flow
- Being involved in a crash (irrespective of whether or not you were to blame)
- Failure to indicate when turning
- Making a quick turn
- Driving on the wrong side of the road
Apart from observing your driving pattern, officers also use field sobriety tests to determine whether you are impaired or not. Here, an officer stops you and asks you to move out of your car to take these tests. Note you don’t have to do field sobriety tests. These tests are only used to gather proof against you to show you were impaired at the time of driving.
The officers mainly use three kinds of tests to collect proof against you for suspected DUI. They include:
The walk & turn test
In this test, the law enforcement officer explains the action he/she wants you to perform. The actions usually include walking heel to toe or by placing one foot in front of the other for a specified length (parking spot lines are frequently used). The officer will then instruct you to turn at a 180-degree angle and walk along the path again.
When walking, the officer is looking to see if you will lose balance, are incapable of following directions, and any other sign that shows the inhibition of your cognitive ability.
The one-leg stand test
Here, the officer again explains the action he/she wants you to perform. For instance, he/she may instruct you to stand on one leg then count from zero to one hundred or recite alphabetical letters backward until he/she tells you to stop.
When doing this, the officer is looking to see whether you can:
- Balance on one leg
- Coordinate properly
- Do both tasks successfully with no errors
- Focus on talking when balancing on one leg.
The horizontal gaze nystagmus test
In this test, the officer instructs you to remove any hard contacts or eyeglasses. Then, without moving your head laterally, you will be instructed to follow the officer’s finger by only using your eyes. You will only return your eyes to the center after the officer tells you so.
When the officer’s finger reaches the far left or right limit, he/she will look at your eyes to see if they are twitching or jerking. Twitching and jerking happen when the muscles of the eye strain to maintain the eyes in position.
Even though field sobriety tests are subjective when it comes to gathering proof of impairment, facts prove that these tests identify a higher BAC in drivers. However, this is only possible when they are properly conducted. When you don’t have a blood-alcohol level that is more than the lawful limit, then field sobriety test results are used as any other proof that may lead to your conviction.
Increased Penalties for Driving with a High BAC
In California, you can get an enhanced sentence if your BAC is way above the legal limit. Generally, the more alcohol you consume, the more you become incapable of driving as a sober person would. In case your blood alcohol level was 0.08% when you were pulled over, you will be subjected to the standard drunk-driving punishment. However, a BAC that is beyond 0.08 subjects you to harsher penalties. Note that the penalties apply even if it is your first offense. They include:
- A driver’s license suspension for ten months. You will be able to obtain a restricted license once you complete serving one month of your sentence and have also completed a nine-month DUI counseling and education program.
- If you are a first-time offender, the court may order you to install an ignition interlock device in your vehicle for up to three years.
- First-time offenders who are on DUI probation and are caught driving with a BAC of .15% are ordered to enroll in an alcohol/drug education program for at least nine months.
Consult a San Jose DUI Attorney Near Me
The main proof that could get you quickly convicted of DUI is your BAC. If it is higher than the legal limit, you need to know how you can challenge the test results so the court can discredit them. Note these results may be falsely high. Therefore, challenging them with valid reasons may have them removed from the prosecution’s evidence. Hiring an experienced DUI defense attorney to handle your case increases your chances of winning. It is also critical to act promptly, especially if you do not want to lose your privilege to drive. For San Jose residents, contact San Jose DUI Attorney Law Firm at 408-777-6630 for a free consultation and legal representation.