Understanding Scientific Evidence In California Drunk Driving (DUI) Cases

There is a vast body of scientific research and literature about how alcohol interacts with and affects the human body.  In fact, there are literally thousands of peer reviewed and journal studies.

Topics range from the way alcohol is absorbed and eliminated, the rates at which it does so, the biological variations among men and woman, and among people of different races and from different global locations.

There is also a body of literature about how to best determine whether somebody is impaired by alcohol, and how to test alcohol levels.

In the courtroom, the studies are often times glossed over because the typical jury does not have the patience or attention span to absorb all of the nuances.

In presenting alcohol science to juries, we take the approach of “less is more,” in most cases. In essence, we pick the most important points that tend to show our clients’ innocence or create reasonable doubt, and then we attempt, through expert testimony, to educate the jury (or judge) about our theory of the case.

Blood testing in California DUI arrests

Blood testing in California, including Orange County and Los Angeles County,  DUI cases is used frequently. As a general rule, blood testing is more accurate and less prone to attack than breath testing. Whenever an California DUI suspect refuses to take a breath test, the police officer has the option of obtaining a search warrant and forcibly taking the defendant’s blood.


This is a good, and evolving, question in California DUI Law. Classically, blood samples in Arizona DUI cases were taken only at hospitals by qualified medical personnel. Recently, however, police officers have started to gain phlebotomist credentials so that they can draw your blood.

There have been DUI cases where a police officer in California literally stabs a suspect with a needle on the hood of a police cruiser. While this is not the norm, it can and does happen.


Absolutely! A flawed blood draw has the potential not only to injure the subject, but to contaminate the sample as well. Improper procedure can result in an erroneously inflated BAC result of more than .20 (which can take a sober diabetic into the realm of an extreme DUI).


YEAST: One source of blood test error/contamination is through the introduction of yeast into the blood sample. Yeast feeds on blood sugars, and the waste product of such consumption is alcohol. This alcohol in the blood is not distinguishable from the alcohol that you drank.

ALCOHOL: If the clinical used to “sterilize” the site of the venipuncture (usually opposite the elbow) contains alcohol, this will get picked up by the needle and introduced into the blood sample.

POOR VACUUM: Each of the grey-topped tubes used in the blood collection kits contains a vacuum used to suck you blood into the tube. If the vacuum is compromised prior to your DUI blood test, it may have sucked environmental contaminants such as yeast, alcohol or other microbes into the tube.

NON-STERILE TOP: The skin is cleansed where it is to be punctured, but the top of the blood test tube is not.

NOT YOUR BLOOD SAMPLE: What if the lab screws up and incorrectly numbers your blood sample? You will get somebody else’s result. How do you tell? Independent DNA testing.

DUI Defense Lawyers

To have the greatest opportunity of avoiding the many penalties and negative consequences of DUI conviction, be sure to contact our experienced DUI attorneys as soon as possible. We are here to offer you the aggressive and dedicated representation you deserve.

The Reynoso Law Firm, with offices throughout Orange County, is a well-respected law firm of DUI lawyers specializing in DUI defense exclusively: no clients but those charged with drunk driving (and related charges) are accepted. Mr. Reynoso has been defending Orange County  DUI cases since 1997,  is a graduate of NCDD’s DUI Trial College conducted at Harvard Law School, and has been named a Top Orange County DUI Attorney by OC Register Metro Magazine (only eight attorneys in the entire state relieved this designation).

We invite you to contact us today for a free consultation about your DUI case.  We will even contact the DMV to protect your license absolutely free, whether you retain our firm or not.

Call 1(877) DUI-PROS now.

Local office numbers are (714)558-1200 or (949) 614-0404.