DUI Chemical Tests in California

Los Angeles DUI Lawyers Serving Southern California

In DUI cases, law enforcement officers and prosecutors both rely on evidence when alleging a motorist was impaired by alcohol or drugs while operating a motor vehicle. During police stops and preliminary investigations, police can use the results of chemical tests (in addition to other forms of evidence such as driving behavior and a driver’s demeanor or physical appearance) to form the basis of their probable cause for making an arrest. Once charges have been filed, prosecutors also use chemical tests in their efforts to convict defendants of driving under the influence.

Because chemical testing is a critical aspect of DUI cases, effective defense strategies should focus on closely scrutinizing and evaluating how chemical tests were administered, their accuracy, their results, and how they relate to the government’s allegations.

At Lessem, Newstat & Tooson, LLP, our Los Angeles DUI attorneys have decades of collective experience fighting for clients across Southern California after they were charged for DUI. While we tailor our defense strategies to the unique facts involved, we always devote time and attention to chemical testing and the role it played in our clients’ cases.

Types of DUI Chemical Tests

There are various chemical tests law enforcement may use to determine whether a motorist is impaired by alcohol and / or drugs. These may include:

  • Pre-Arrest PAS Tests – Preliminary Alcohol Screening (PAS) tests refer to the chemical testing law enforcement officers may use in the field when they stop and investigate suspected impaired drivers, prior to arresting them. These PAS devices are a type of handheld breathalyzer, and they can be used to gain an understanding of whether or not a driver has alcohol in their system. It is important to know that these PAS tests are not 100% effective, and that they can be prone to error, especially when improperly maintained or when results are affected by certain factors (such as mouth alcohol from mouthwash, improper administration, and more). They are also not mandatory, and can be refused without consequence (though any requested breath or chemical test following an arrest at a police station or local jail cannot be refused without penalty).
  • Breath Tests – Breath tests can include the PAS tests mentioned above, or tests conducted using larger machines at a local police station or jail. If a driver refuses the initial PAS test, they cannot refuse any subsequent breath or chemical test following an arrest without risking an automatic driver’s license suspension. Just as with the PAS tests, these breathalyzers are not infallible, and they can produce inaccurate results due to calibration errors, poor upkeep, mechanical malfunction, and more.
  • Blood Tests – Drivers stopped under suspicion of DUI may be asked to take blood tests at a local station or jail, regardless of whether they accepted or refused an initial PAS test. Blood tests can also be administered to drivers regardless of whether officers suspect intoxication by alcohol, drugs, or both. When warrants are obtained for blood tests in DUI cases, suspects cannot refuse them without risking penalties (automatic driver’s license suspension). These blood tests can also be subject to various factors that compromise the accuracy of results, including improper handling of blood samples, calibration issues, and more. In some cases, such as those involving marijuana DUI, blood tests may also not be a reliable indicator of whether a driver was actually under the influence at the time of their arrest.
  • Urine Tests – While law enforcement can request suspects to take urine tests, these tests are not commonly used in cases involving DUI.

Chemical Test Refusal

In California, all motorists are subject to the state’s law of “implied consent,” meaning they implicitly give their consent to take chemical tests when lawfully arrested under suspicion of DUI. This rule may not apply to PAS tests administered in the field, but it does apply to the subsequent breath and blood tests that may be administered at a local police station, jail, or other booking facility. When drivers violate this law and refuse chemical testing in DUI cases, they risk a few significant consequences, including:

  • Mandatory suspension of your driver’s license (regardless of the outcome in any criminal DUI case);
  • Potentially elevated penalties in addition to standard DUI penalties (including additional time in jail and / or longer terms for mandatory DUI school).

The operative word when it comes to chemical tests and the law of implied consent is “lawful” arrest. If a law enforcement officer does not have sufficient reason to justify their stop or any further investigation, they violate procedural rules and your rights when asking you to take an unwarranted chemical test. Investigating whether or not officers had reasonable suspicion to stop you and probable cause to believe you may have been driving under the influence is critical to protecting your rights and raising a defense involving unlawful search and seizure.

Discuss DUI Chemical Testing & Your Charges During a FREE Case Review

Evaluating and challenges all aspects of chemical testing that may or may not have been used in your DUI case is critical to ensuring your rights were not violated and that tests are not affected by factors that could account for erroneous results. As mentioned, law enforcement officers and the devices they use are not immune from error, and delving further into how they were used in your case can help provide direction for your defense, including motions to dismiss your case entirely, raise reasonable doubt, and otherwise fight for the most positive outcome possible.

If you have questions about a recent DUI charge and how Lessem, Newstat & Tooson, LLP can fight for you, please call (800) 462-7160 to request a FREE case evaluation. Our firm serves clients throughout the San Fernando Valley, Los Angeles County, Ventura County, and beyond.