DUI defenses

Alcohol DUI


Although most people charged with DUI just plead guilty, don’t assume that you have to follow the herd. We have gotten hundreds of DUIs dismissed, and each case started with evidence which the prosecution believed was enough to win a conviction for DUI, but didn’t, because the Law Office of Jeff Yeh stepped in.

Driving under the influence of alcohol is made illegal because the alcohol in the bloodstream impairs the brain’s ability to function normally. Thus, what is important in determining the level of impairment is the alcohol content IN THE BLOODSTREAM (BAC) and AT THE TIME OF DRIVNG. If what is measured does not reflect what was in the bloodstream at the time of driving, then the results have no rational basis to support a DUI conviction. Moreover, if what is tested becomes contaminated, then the results must also be discredited.

BREATH TESTS: Breath machines are accurate, but the results often aren’t! As ironic as that sounds, it is true. Breath machines are very good at measuring what comes into it. The problem is, what comes into it is often not reflective of what it is designed to measure: a person’s Blood Alcohol Level at the time of driving. Consider the following:

1. Mouth Alcohol – breath machines are designed to measure air, not liquid. When you drink alcohol, some of it gets stuck in between your teeth. Likewise, when a person burps, liquid alcohol gets mixed up with saliva. While this type of mouth alcohol may seem minimal, it certainly isn’t so minimal for a breath machine that is designed to measure the alcohol in a person’s breath, not saliva. What makes it worse is that police officers are known for requesting that you blow into a breathalyzer as hard as you can for as long as you can. Anyone who has played a trumpet or blown into a balloon knows what happens when you blow into something forcefully—saliva gets spit out. In the case of a DUI, the BAC measured can be many times higher due to the presence of mouth alcohol.

2. Rising BAC – depending on the length of time and amount of consumption, a person’s Blood Alcohol Level can continue to rise several hours after the last drink. For example, suppose it is 11pm and you just had your last drink and you are driving home, you could be at a 0.06%, but by 12am or 1am, when you are administered a chemical test at the police station, you may register a 0.09% or higher. In other words, the results obtained simply do not reflect your BAC at the time of driving.

3. Absorption – as mentioned above, what makes DUI illegal is the alcohol in the bloodstream that impairs the brain. The problem with breath machines is, it works by measuring BREATH and converting it to a BLOOD Alcohol reading. So if the “breath” reflects a 0.10% BAC, but the “blood” actually contains only a 0.03% BAC, then you can see how an innocent person gets convicted of DUI. The fact is, when a person is still absorbing alcohol and blows into a breathalyzer, the results will ALWAYS read higher, sometimes 3-5 times higher! The reason is, the person is still absorbing alcohol, a process that can take up to several hours especially if there is food in the stomach. During absorption, the alcohol consumed has not had sufficient time to fully enter the bloodstream, so the “breath” alcohol measured can be a far cry from the “blood” alcohol, which is what affects the brain. Remember that DUI statutes refer to “BLOOD Alcohol Level,” not breath!


Blood tests are generally more accurate than breath tests, because blood is measured directly and no conversion from breath is necessary. However, in addition to being vulnerable to the Rising BACattack (see above), blood samples are often not maintained properly, and the results can be just as skewed. Consider the following: 1. Fermentation – after blood is drawn and put in a vial, Title XVII requires that an anticoagulant and a preservative be placed in the vial, which must then be shaken. The anticoagulant prevents the blood from clotting, and the preservative prevents fermentation, whereby the blood goes bad—much like sour milk —and the alcohol content multiplies. The problem is, most blood vials in DUI cases sit in the police station un-refrigerated for several weeks before someone even gets to the task of evaluating it. This is coupled with the fact that law enforcement is often unfamiliar with the requirements of Title XVII, and do a poor job documenting the chain of custody of the vial. This means that the BAC obtained from the “contaminated” sample can be much higher than the BAC of the same sample the day it was drawn from your arm!

At trial, the prosecution expert will always make the assumption that you are “fully absorbed” at the time of driving, so that your BAC can only be falling (instead of rising or peaking) up to the time of the test. A defense expert can often show that this assumption has no basis in reality.


Most people who are arrested at a DUI Checkpoint never question the legitimacy of the Checkpoint itself. The fact is, Checkpoints have to be properly set up and maintained, or else the stop (and the subsequent DUI) is illegitimate.

For example, a Checkpoint must be set up at a time and place that makes sense, yielding enough DUI arrests to outweigh the burden to the public. Moreover, signs must be set up to warn drivers in advance, with escape route(s) for drivers who wish to avoid it.

Remember, it is up to the the state to prove that the Checkpoint is legit (once the defendant has raised the issue). Never assume that it is!

The Law Office of “The DUI Specialist” Jeff Yeh is proud to serve clients in all of Los Angeles, Ventura, Orange, San Diego, Riverside, and San Bernardino counties. The firm handles DUI and criminal cases in Torrance, Long Beach, South Bay, Downey, San Fernando, Santa Monica, Westminster, Santa Ana, Newport Beach, Hawthorne, Fullerton, Laguna Niguel, Alhambra, Hollywood, Yorba Linda, Redondo Beach, Manhattan Beach, Burbank, Pasadena, Santa Clarita, Valencia, Newhall, Whittier, West Covina, Calabasas, Garden Grove, Tustin, Foutain Valley, Anaheim, Inglewood, Buena Park, Cerritos, Lakewood, Los Alamitos, Bellflower, Norwalk, Chino, Carson, Redondo Beach, Orange County, Los Angeles County, San Diego County, Ventura County, Riverside County, San Bernardino County, El Monte, Manhattan Beach, Gardena, Compton, South Gate, La Puente, Pomona, Costa Mesa, San Clemente, Mission Viejo, Laguna Beach, San Pedro, Glendale, Beverly Hills, Culver City, Temple City, Westwood, Van Nuys, Woodland Hills, Encino, Sun Valley, La Canada, Altadena, Sierra Madre, Monrovia, Azuza, La Verne, Pomona, West Hollywood, Marina del Rey, Chatsworth, San Fernando, Orange, Placentia, La Crescenta, Corona, Bellflower, Rosemead, Montebello, San Dimas, Vernon, Monterey Park, San Gabriel, Diamond Bar, Sherman Oaks, Eagle Rock, Bel Air, Chino Hills, Brentwood, Simi Valley, Lancaster, Fontana, Riverside, Big Bear, Barstow, Indio, Murrieta, Blythe, and all other cities in Southern California.

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