How Matthew Ruff Wins Cases Using Rising BAC Defense

 The defense of Rising Blood Alcohol is a way to challenge the results of a breath or blood test by showing the results are not reflective of the person true BAC at the time of driving.  You see, in California the law prohibits driving when your blood alcohol level is at or above .08.  If the facts show the individual was in the absorptive state of alcohol metabolism when he was stopped it can be argued his or her BAC at the time of the test was higher then when they were actually driving.  

Matthew Ruff wins DUI cases using the Rising BAC Defense when the evidence shows they had recent drinking, close in time to the stop.  If the last drink or drinks were consumed within 1-2 hours (longer in cases where some prescription drugs are being taken) of the time of the stop they may still have raw alcohol in their stomach which hasn’t been absorbed in the blood stream and therefore is not a “blood alcohol concentration”.  

The science on the subject is quite clear: The absorption of alcohol is a complex dynamic process that begins as soon as drinking begins. Alcohol is primarily absorbed into the bloodstream through the small intestine, but some absorption occurs in the stomach and mouth. Absorption rates are highly variable and are not linear. Factors such as the presence of food in the stomach, the type and volume of beverage consumed, other drugs consumed, and the condition of the gastrointestinal tract, can impact absorption rates. Studies support that it can take up to 2 hours or longer to reach the post absorptive phase after the last drink The time needed to reach the peak alcohol concentration is not the same as the time to reach the post absorptive phase.

What this means is that if you are arrested and charged with driving under the influence and you took a breath or blood test that resulted in a BAC determination that you were above the legal limit, that determination could be subject to challenge if your last drink or drinks were within 2 hours of the chemical test, or longer in some cases where the person is taking certain medications.  For example, if you are taking Ozempic or similar drugs absorption times can be increased.  Read Matthew’s post about how Drugs like Ozempic may lead to false BAC results in DUI cases.

In a recent case Matthew was able to get charges dropped and a client’s license reinstated after he presented evidence using back extrapolation to show the BAC was below .08% at the time of driving. 

Victory at the DMV: How Top-Rated DUI Attorney Matthew Ruff Secured a Total Set-Aside Using the "Rising BAC" Defense

When facing an Administrative Per Se (APS) driver's license suspension from the California Department of Motor Vehicles (DMV), many drivers assume the odds are entirely stacked against them. However, experienced legal representation can uncover crucial technical and scientific defenses to completely reverse these actions.

Recently, top-rated California DUI defense attorney Matthew Ruff achieved a major victory at a DMV administrative hearing, securing a complete **Order of Set Aside** for a client facing a mandatory license suspension. The win showcases the power of the “Rising BAC" defense” when paired with meticulous case analysis.

The case began following a minor traffic incident in Hermosa Beach. Law enforcement responded to a call regarding a vehicle that had side-swiped a parked car in a local parking lot. The driver subsequently returned to the scene and cooperated with the responding officers.

During the contact, officers noted objective symptoms of intoxication, including red, watery eyes and an unsteady gait. After performing Field Sobriety Tests (FSTs), the driver was arrested for driving under the influence.

Later at the police station, the driver was subjected to an evidentiary chemical breath test. The results from the DataMaster DMT instrument revealed:

* **First Sample (19:08):** 0.11% BAC

* **Second Sample (19:11):** 0.11% BAC

Because the results were well above California's legal limit of 0.08%, the DMV immediately initiated an administrative suspension against the client's driving privileges.

Anatomy of the Win: The Rising BAC Defense

Faced with a 0.11% chemical test result, many boilerplate defenses fall short. However, Matthew Ruff thoroughly analyzed the precise timeline of the stop, the driver's statements, and the scientific mechanics of how the human body processes alcohol.

The defense heavily relied on the timeline established in the official police reports:

* **Time of Last Drink:** The client stated they finished drinking at approximately 13:10 (1:10 PM).

* **Last Consumption of Food:** The client had eaten a variety of foods (nuts, pickles, cheese, and chips) up until 17:00 (5:00 PM).

* **Time of Driving/Incident:** The collision occurred around 16:53 (4:53 PM), and the client was contacted by police around 17:58 (5:58 PM).

* **Time of Chemical Test:** The breath samples were taken at 19:08 and 19:11 (over two hours after the alleged driving took place).

What is the "Rising BAC" Defense?

Under California law, it is illegal to have a BAC of 0.08% or higher at the time of driving.  When a person consumes alcohol or has food in their stomach delaying absorption, their blood alcohol level can continue to rise long after they get behind the wheel. If the chemical test is taken hours later, it may reflect a peak BAC that was significantly lower—or even below the legal limit—while the person was actually operating the vehicle.  

Retrograde Extrapolation 

By highlighting the delayed testing timeline and leveraging the client's specific food and alcohol consumption window, Matthew Ruff successfully argued that the DMV could not conclusively prove the client's BAC was at or above 0.08% at the exact moment of driving.

The Outcome: License Fully Restored

Following a meticulous review of the evidence presented by the defense, the California Department of Motor Vehicles Legal Affairs Division officially ruled in the client's favor.

On November 17, 2025, the DMV issued an official **Order of Set Aside**, completely erasing the administrative suspension that had been put into motion. The client was cleared by Driver Safety, required no SR-22 financial responsibility filings, and was permitted to simply print a duplicate license and return to the road with a completely clean driving record.

This case serves as a powerful reminder that a high breathalyzer reading is not an automatic conviction. With the right legal advocate identifying gaps in the state's timeline, your driving privileges can be protected.

If you or a loved one are facing a California DUI or a DMV Administrative Per Se suspension, don't leave your future to chance. Contact the Law Offices of Matthew Ruff today for a comprehensive evaluation of your case.

Landmark DUI Victory: Top-Tier Defense Shoves "Retrograde Extrapolation" Into the Spotlight to Beat the State’s 0.08% BAC Case

LOS ANGELES, CA — Can you successfully win a DUI case using retrograde extrapolation and a rising blood alcohol concentration (BAC) defense? Yes. A recent California case defended by prominent DUI Attorney Matthew Ruff proves exactly how a meticulously calculated scientific defense can completely dismantle the prosecution’s timeline.

Through a precise timeline reconstruction, a premier DUI defense team successfully demonstrated that the state’s chemical testing failed to prove the driver was over the legal limit at the actual time of driving.

The Timeline: A Modern Case Study in "Rising BAC"

On October 11, 2021, a motorist was contacted by California law enforcement officers at approximately 6:18 PM. The driver openly admitted to having drinks earlier in the afternoon, starting around 4:30 PM.

The state based its entire prosecution on three separate chemical test numbers taken well after the driving had ended:

• 6:50 PM (32 minutes post-driving): The first Preliminary Alcohol Screening (PAS) test registered at 0.124%.
• 6:54 PM (36 minutes post-driving): A second PAS test registered at 0.105%.
• 8:16 PM (1 hour and 58 minutes post-driving): A formal blood draw at a local hospital resulted in a raw average of 0.08% (specifically duplicate testing at 0.078% and 0.082%).

 6:18 PM             6:50 PM            8:16 PM
[Driving Ends] ---> [PAS: 0.124%] ---> [Blood: 0.08%]
 

Deconstructing the Science: Why the State's Case Collapsed

The prosecution attempted to use the 0.08% blood result—the exact legal threshold under California Vehicle Code §23152(b)—to secure a conviction. However, a top-tier DUI defense relies on science, not assumptions. By utilizing retrograde extrapolation—the mathematical process of calculating a person's BAC backward in time—the defense proved that the driver's BAC was actively fluctuating and, crucially, under the legal limit at 6:18 PM, the exact moment they were behind the wheel.

The Core Defenses:

• The Rising BAC Reality: Alcohol takes time to fully absorb into the bloodstream, especially when paired with a heavy meal (the driver had consumed a double chili burger combo earlier that afternoon). At 6:18 PM, the body was still actively absorbing the alcohol, meaning the BAC was below the legal limit while driving and peaked after law enforcement intervened.
• The Flawed Evidentiary Peak: The wildly divergent PAS tests (0.124% down to 0.105% in just four minutes) highlighted massive absorption volatility and device margin of error.
• The 99% Confidence Interval Loophole: The Scientific Services Bureau conceded that the 0.08% blood result carried an expanded uncertainty margin of \pm0.004\%. This scientifically established that the driver’s actual blood alcohol level could have legally been as low as 0.076%—instilling undeniable reasonable doubt.

"Science Wins Cases, Not Police Observations"

"This case is a textbook example of why drivers should never assume a chemical test reading equals a guaranteed conviction," said the lead defense counsel. "The law doesn't care what your BAC is at a hospital two hours after the fact; it only cares about your sobriety while operating the vehicle. By pairing the science of retrograde extrapolation with the mathematical margin of error provided by the state's own crime lab, we successfully protected our client's future."

This definitive victory sets a powerful precedent for motorists facing borderline chemical test results across the state, proving that a rigid timeline and forensic pharmacology remain the ultimate shield against overzealous DUI prosecutions.