Contact Us for a Free Case Evaluation (951) 405-0990


Should I take a blood or breath test if I am arrested for DUI?

Posted by Steven McNicholl | Jun 27, 2019 | 0 Comments

Under California's implied consent law, you must submit in most cases to either a blood draw or breathalyzer once placed under arrest for driving under the influence (DUI).  Refusing to take a chemical test results in harsh penalties including a mandatory one-year long suspension of your driver's license with no possibility of obtaining a restricted license.  This means you will not be able to drive for the next year.  This is meant to be a huge deterrent for those thinking of refusing to take a chemical test to avoid exposing their blood alcohol concentration.  So assuming you want to submit, which is the better choice for you and your case?  Let's examine each choice inpidually.

Should you take a blood test?

​The blood test will require a registered to perform a blood draw on you at your local detention center.  Your blood sample will then be shipped to a laboratory to be analyzed to determine your blood alcohol concentration directly in your blood stream.  Blood samples are more accurate than breath samples as not only is your blood alcohol concentration directly measured, the blood sample will eliminate other possible sources of interference in the results that a breath sample would display.  A blood draw is, legally speaking, a more complicated procedure.  An officer is required to obtain your consent to draw blood if he does not have a search warrant for your blood.  Yes, oddly an officer must have a search warrant for your blood according to recent court cases.  Any misstep by an officer could result in evidence not being admissible against you in court greatly helping your cause.  

Should you take a breath test?

​The breath test will require you to provide breath sample by breathing into a machine with a sufficient volume.  The machine works by analyzing air from deep within your lungs to sense the presence ethyl alcohol.  The amount of ethyl alcohol in your lungs is used to estimate your blood alcohol concentration using a mathematical formula.  And yes, before you start, the math is good and reliable.  The problem with the breathalyzer is that the results are subject to interference caused by common items.  The machine cannot differentiate between mouth wash and mouth sprays.  The gasses from acid reflex disease in your mouth similarly impacts the results of a breathalyzer significantly.  A recent study found, a specific brand called “Binaca” breath spray caused the breathalyzer to read .81 when no alcohol was consumed and the breathalyzer continued to register high results for 18 minutes.1  The ease of confusing and interfering with the breathalyzer clearly makes it the most inaccurate choice.  But, be careful as the accuracy issues almost always increase the blood alcohol concentration results.  

Which test should you take then?

In most DUI arrests involving alcohol, it will come down to a choice between a blood draw and a breath test.  The important question is, which should you take?  Like everything in the law, it depends.  The blood sample requires very specific warnings from the officer and your consent to the blood draw.  It is also significantly more accurate than the breath test.  The accuracy will benefit you if you are below a BAC of .08 percent.  Are you feeling strongly that your BAC is below .08?  The blood test may be the way to go for you as you may be exonerated from your DUI when the results come back.  Are not so sure whether your BAC is high or not?  The breathalyzer may be the way to go for you.  A high result may be contestable in your criminal case.  The officer will likely not know whether you had mouth wash residue in your mouth or that you vomited in your mouth, casting serious doubt on the results of the breathalyzer. In short, which test should you take if you are arrested for DUI?  If you want the accuracy go for the blood test and if not go for the breathalyzer.  Have you already been forced to make this choice?  Call the Law Offices of Steven McNicholl at (951) 405-0990 for a free analysis of whether you made the best choice.

You can read more about DUI/DWIs here 

About the Author

Steven McNicholl

Steven McNicholl is a criminal defense attorney serving clients in Southern California.  He has the experience necessary to bring intensity and focus to every case ensuring you receive the dedication and vigorous defense you require in your case.


There are no comments for this post. Be the first and Add your Comment below.

Leave a Comment

Contact Us Today!

If you or a loved one has been charged with a crime, call the Law Offices of Steven McNicholl at (951) 405-0990. We have the skill and experience in San Bernardino County to protect your rights and get the best results in your case.

California Criminal Defense Lawyer Disclaimer: The legal information presented at this site should not be construed to be formal legal advice, nor should it be considered the formation of a lawyer or attorney-client relationship. Any case results presented on the site are based upon the facts of a particular case and do not represent a promise or guarantee. The contents of this website may contain legal advertising. If you would like to find out more information about your particular legal matter, contact our office for a free telephonic consultation. This web site is not intended to solicit clients for matters outside of the state of California.