Top Ten Tips > Fighting a DUI Arrest

7. The 3-Hour Presumption

Relating Back.

Police officers are never able to test your blood alcohol precisely at the time you are driving. Your Sonoma County DUI lawyer will explain to you that typically at least 10-40 minutes elapse, sometimes more than an hour or two subsequent to driving, particularly in accident cases and during busy holidays. Therefore the law provides the government with a presumption that as long as the test samples are obtained within three hours of driving, the law will presume that the result obtained subsequent to the DUI arrest relates back to your alcohol level at the time of driving (Vehicle Code Section 23152(b)). If the test sample was not obtained within 3 hours, then the government cannot rely on this presumption and you may very well have a winning case in Sonoma County Superior Court and at the Santa Rosa DMV.

Understand that the 3-hour rule is a rebuttable presumption, a legal fiction which may be challenged with our own affirmative evidence, introduced in a Sonoma County court or at the Santa Rosa DMV, that the test is not an accurate reflection of your alcohol level at the time of driving. The best example is evidence of drinking after driving, even if the drinking happens in the vehicle once it has been parked. Good Santa Rosa DUI attorneys will tell you that one of the most common mistakes in such circumstances is denying this defense of drinking after driving at the time of arrest out of fear that it would make things look worse to the arresting officer. See this discussion under Tip #4 above.

Passed outTime of Driving.

Obviously, in order to take advantage of this gift of a 3-hour presumption, the government (both the Sonoma County District Attorney and the Santa Rosa DMV) must be able to establish a time of driving with some degree of probability. Sonoma court and DMV cases may be winners if, for example, your Sonoma County DUI attorney can show that you were parked for more than a couple of hours, perhaps sleeping off the liquor, prior to encountering law enforcement, or if an accident scene is undiscovered for a long time. Often your DUI lawyer can use impartial witness testimony, bar receipts, phone messages, and cell phone records to establish driving outside three hours (see the Preserve Physical Evidence discussion in the Tips for the First 48 Hours Articles on this site). DUI attorneys can expect to encounter contrary government evidence of time-stamped dispatch records, evidence of the public visibility of an accident scene, evidence of recency of driving (you in the driver's seat, warm hood, keys in ignition, engine running, lights on), or an eye witness who may have called 911 to report erratic driving at a certain recorded time, all to challenge the possibility that your vehicle had not been stationary for a long time.


Any result portrayed was dependent on the facts of that case, and the results will differ if based on different facts.

About Jake

Dave Jake Schwartz is an Honors Graduate from UC Hastings Law School, former Federal Judicial Clerk, and Nationally Qualified Sobriety Tests Practitioner. Member of the California Bar for nearly 30 years, lived in Sonoma County over 20 years, DUIs only, handled thousands of Sonoma County DUIs and DMV hearings: first/multiple offenders, minors, seniors, tourists, immigrants, veterans, probation violations, suspended license, public intox, open container, minor in possession, collisions, hit and run, evading, child endangerment, and DMV Hearings: medical, negligence, lack of skill, and excessive points.

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Dave Jake Schwartz