Chemical Testing

Chemical Testing

Chemical testing is a key issue in every California DUI case. Accused drunk drivers often fear that if the machine says they are above the legal limit, they are inevitable guilty. However, there are many challenges to the validity of blood, breath, and urine tests in driving under the influence cases. An experienced DUI defense attorney from The Kavinoky Law Firm has an arsenal of proven strategies available to attack the results of chemical tests in driving while intoxicated cases.

Most California DUI arrests result in two separate charges – violation of the “common law” and violation of the “per se” laws. Common law drunk driving charges hinge on whether the motorist was impaired by alcohol and/or drugs, and was unable to operate a vehicle with the same caution as a sober person.

A per se charge focuses solely on whether the driver’s blood or breath alcohol content (BAC) was above the legal limit, now.08 percent in all 50 states. When attempting to prove a per se charge, the prosecutor focuses on the driver’s BAC to prove that the driver was impaired or affected by alcohol.

Chemical testing of the blood, breath, or urine is therefore central to the per se charge, where the defendant is accused of driving above the legal limit. However, chemical tests are also a critical aspect of the common law in a drunk driving case, which focuses on whether or not the driver was impaired. This is because many experts believe that all drivers are impaired once they are above a certain BAC.

Some forensic experts believe that everyone is impaired when their BAC reaches.10 percent, others  .08 percent, and the most conservative think that everyone is under the influence at .05 percent BAC. Therefore, it is vital that a DUI defense lawyer be able to successfully address these issues to advance their client’s cause.

Chemical testing is so critical in California DUI cases that both the DMV and the courts punish drivers who refuse to submit to chemical testing when lawfully requested to do so after a drunk driving arrest. A refusal to test following a drunk driving arrest may result in a DUI.

In a drunk driving court case, a chemical test refusal is a special allegation that, if proven, results in mandatory jail terms, lengthier alcohol education programs, and a jury instruction that allows jurors to consider the refusal to test as consciousness of guilt.

Chemical testing in drunk driving cases or DUI drug arrests involves the testing of bodily fluids: blood, breath, or urine. In most states, when someone is accused of driving under the influence of alcohol, he or she has a right to take either a breath or a blood test.

Where driving under the influence of drugs is suspected, the chemical test choices will usually include blood or urine. Generally, there is no right to a urine test in drunk driving cases. Urine testing in drinking and driving cases has been deemed too unreliable to withstand courtroom challenges.

There are many effective defense challenges to chemical tests in drunk driving cases. While a chemical test may accurately determine BAC at the time of testing, it is not conclusive evidence of BAC at the time of driving. Remember, it isn’t against the law to exceed the legal limit while in a police station; the crime is driving under the influence, or driving above the legal limit, not having a BAC above the legal limit at a later time. Because alcohol levels change over time, this is a critical point to understand.

Chemical testing for alcohol or drugs isn’t always accurate – far from it. There are challenges to breath tests, forensic blood tests, and forensic urine tests. Testing in DUI drugs cases is even more challenging than testing for alcohol levels in a drunk driving case. Drug tests search for metabolites in the blood or urine, not the drug itself. Plus, there are no per se limits in drug cases. Due to the timing many drugs stay in the system, it is incredibly difficult to demonstrate that a person was impaired at the time of driving.

Many drivers accused of DUI believe that a chemical test that shows a BAC greater than .08 percent means a slam-dunk conviction, but that’s simply not the case. However, effectively fighting a driving under the influence case isn’t for amateurs. It’s critical to consult with a California criminal defense attorney with experience fighting drunk driving cases. A skilled attorney can challenge the results of blood, breath, or urine tests, and plan a strategy to fight a drunk driving case.

Alcohol & The Body

In California DUI cases, evidence about the driver’s blood alcohol content (BAC) can be the most damning or the most vindicating evidence in court. It all depends on how the driver’s BAC was affected. Therefore, it is important to have a clear understanding of how the body absorbs, distributes, and eliminates alcohol. The skilled DUI criminal defense lawyers at The Kavinoky Law Firm are well-versed in the science of alcohol metabolism and will use this information to challenge chemical test results and help a motorist fight a drunk driving case.

DUI prosecutors regard a driver’s chemical test results as one of the most important pieces of evidence in a California driving under the influence case. However, everyone metabolizes alcohol differently, so it is extremely difficult to look back in time to accurately pinpoint BAC when the driver was behind the wheel. This difficulty increases with the passage of time and becomes increasingly speculative.

In addition, the integrity of a blood test hinges on whether the sample was properly collected, stored, and tested. Clearly, for the DUI criminal defense attorney whose expertise lies in highlighting reasonable doubt as to any element of the criminal case, this becomes increasingly valuable.

When an individual takes a drink of alcohol, it isn’t absorbed into the body right away. It first enters the stomach and then the small intestine where most of the absorption takes place. How fast the alcohol is absorbed depends on the type of drink consumed, the individual’s stomach contents, and many other factors.

The body starts eliminating alcohol immediately, but cannot dispose of it at the same speed at which it is absorbed. This is how an individual’s BAC rises. The body is like a bathtub with a slow drain; the water flows in faster than it flows out, and so the level increases. Alcohol absorption in the human body occurs in much the same way.

The body continues to absorb alcohol even after an individual stops drinking, and the BAC continues to rise until it reaches a plateau. This peak represents a perfect equilibrium – absorption and elimination of alcohol is occurring at the same rate, so the alcohol level flattens out and is consistent for a period of time. This plateau typically lasts for 15 to 45 minutes, depending upon stomach contents and metabolic rate.

After the body’s blood alcohol content plateaus, the elimination phase begins. If the individual stops drinking, the BAC will steadily decrease at an average rate of approximately .02 percent per hour – about the equivalent of one drink. This too varies widely from person to person and in situation to situation.

The process of alcohol metabolism is represented graphically like a bell curve. Because a driver’s BAC continues to rise after he or she stops drinking, a chemical test that shows that the driver was above the legal limit of .08 percent BAC doesn’t mean he was intoxicated while behind the wheel.

Many experts agree that breath-testing during the absorptive phase – after a driver stops drinking, but before alcohol content peaks – can overestimate true alcohol levels by 40 to 100 percent.

Many factors can affect the results of a chemical test in a driving under the influence investigation, including the motorist’s metabolic rate, stomach contents, and fatigue level. Often, an officer’s roadside investigation doesn’t even begin to address these issues. A skilled California DUI criminal defense lawyer can devastate the prosecution in a drunk driving case during an effective cross-examination.

Roadside Breath Testing

Many drivers arrested for DUI in California take a roadside breath test to determine blood alcohol content (BAC) before being arrested. Although police and prosecutors believe PAS (Preliminary Alcohol Screening) test results are damning evidence in drunk driving cases, these results can often be successfully challenged in court. An experienced California criminal defense attorney who specializes in DUI cases has the skills needed to effectively challenge PAS tests in driving under the influence cases.

DUI criminal defense attorneys have been dealing with the problems that arise with roadside breath testing for years. In the early days of roadside breath testing, it was accepted that the technology was somewhat inferior, and that roadside PAS tests were not reliable enough to be admitted into evidence. Therefore, if police used an alcohol screening test during a drinking and driving investigation, the only thing that could be introduced in evidence at a DUI trial was that the PAS machine that indicated the presence of alcohol – the numeric results were excluded.

Unfortunately, that is no longer true. Courts hearing DUI cases now allow the numeric results of the PAS tests to be considered by the jury if certain evidentiary foundations are established. Therefore, motorists are taking roadside breath tests after being advised that their participation is entirely voluntary, only to have the numeric results introduced at trial.

There are two types of roadside breath tests – PAS or PBT tests. This are merely screening tests given to support the officer’s decision to make an arrest, and roadside evidence. There are critical distinctions between the two.

The PAS, or preliminary alcohol screening, is a voluntary test. It is not an “implied consent” test, which means that the driver is under no obligation to take a PAS test. In fact, in many states, the officer must advise the driver that the test is not required, but if an arrest is made, the driver will then be required to submit to a test of his or her blood or breath to determine alcohol content.

Unfortunately, many police officers ignore this responsibility during drunk driving roadside investigations. Many times, the driver is told that he or she must submit to a test as a collection tube is thrust into the mouth of the awestruck motorist. A DUI arrest invariably follows. It likely would have followed anyway, except now the unwitting motorist has provided additional evidence for the government to use against him or her.

The recent addition of the evidential PAS test, also known as the “E-PAS” or AlcoSensor IV XL, has made roadside DUI investigations even more complicated. These versions of the roadside breath test are the evidential tests required under the Implied Consent Law. The exact same machine that is used to administer this mandatory test was, moments earlier before the driver was arrested, an optional test. The only difference is that they are able to print out the results instead of merely viewing the results on an LED readout.

Unfortunately, accused drivers are often unable to pinpoint the moment that they are placed under arrest for drinking and driving. One minute they are offered a roadside test, and told it is optional. A moment later, they are told that a roadside breath alcohol test on the same machine is mandatory. It isn’t hard to understand how a driver can become confused. This is why many DUI criminal defense lawyers advise people to refuse all roadside breath tests and insist upon a blood test if they are ever the target of a drunk driving investigation.

Once an arrest is made, California’s Implied Consent Law is triggered. A failure to give a blood or breath sample following a drunk driving arrest can result in administrative sanctions from the Department of Motor Vehicles (DMV). These sanctions begin with a one-year driver’s license suspension, with no opportunity for a restricted or provisional license during that year.

Roadside breath testing addresses a significant issue in drunk driving prosecutions. Due to the typical time-lapse between driving and testing, oftentimes the issue of whether the driver’s BAC could have been below the legal limit at the time of driving presents itself. The aim of roadside breath testing in drunk driving cases is to eliminate that issue by fixing the blood or breath alcohol level (BAC) at a time closer to the time of driving.

While this may have been a worthy goal, there are significant problems that overshadow the advances made. The challenges to both the PAS test (pre-arrest roadside breath test) and the E-PAS (the post-arrest roadside breath test ) are the same because they are taken on the same machine. The distinction is that the E-PAS is hooked up to a printer, providing the DUI arrestee a copy of the printout of the faulty device.

The inherent flaws in breath testing work to the advantage of the accused drunk driver. DUI prosecutions are just like any other criminal case; in order for prosecutors to get a conviction, they must prove each element of their case beyond a reasonable doubt. If the prosecutor is unable to present a case that is 100 percent free of reasonable doubt, the driver cannot be convicted. This is the requirement in every criminal case, whether it is driving under the influence of alcohol, DUI drugs, vehicular manslaughter, robbery, murder, or any other offense.

In order for a breath test to prove a motorist’s guilt beyond a reasonable doubt, there are certain evidentiary foundations that must be observed. Thus, the most basic challenge to breath tests lies in the calibration, maintenance, and accuracy of the testing machine. Both field breath testing units and station-house breath testing units are subject to problems, and it is vital to explore these issues in every drunk driving prosecution.

It’s also critical to determine whether the officer who gave the breath test was qualified to do so. There are rules and regulations regarding the administration of breath tests. It is imperative that only those with the appropriate training perform these tests on motorists suspected of driving under the influence of alcohol.

One effective challenge to roadside breath tests relates to the technology of the machine itself. The roadside PAS devices are “fuel cell” machines. Alcohol is oxidized on an electromagnetic plate, and the amount of electrochemical energy generated is converted to a number that is supposedly equal to the blood-alcohol level of the motorist.

This technology creates the possibility that other compounds in the human breath will be misinterpreted as alcohol, and deliver inflated BAC results. Mouth alcohol is one factor that can skew the results of a breath test.

Mouth alcohol is one of the most significant problems with forensic breath testing. The danger of mouth alcohol contamination instigates many of the rules and regulations in breath testing, such as a 15- or 20-minute waiting period, observing the subject to ensure they do not regurgitate or introduce foreign material in the mouth, and the requirement of obtaining two similar results. These are all critical issues in DUI cases, especially in those involving the PAS machine.

PAS machines don’t have mouth alcohol detectors, also called slope detectors. A slope detector is a computer software program that is designed to detect a rapid drop-off – or slope – in the alcohol level of an individual’s breath sample. The machine is not smart enough to know whether it is analyzing alcohol molecules in the deep lung air – which it is supposed to be measuring – or alcohol molecules that have been trapped in the mouth or regurgitated from the stomach. This is particularly problematic when the driver is given a breath test shortly after drinking, while alcohol is still in the stomach, or has been trapped in the mouth due to dental work, food traps, or other factors.

PAS tests also lack the ability to measure breath temperature. Every calculation the machine makes is based on the assumption that the subject’s breath temperature is 34 degrees centigrade. Unfortunately, just like the other assumptions that are made about the so-called “average” person, any variation from “average” can greatly impact the reading. Every degree of temperature elevation – which could be from illness or activities like dancing or sports – equals a 7 percent increase in alcohol percentage.

Many motorists targeted for drunk driving investigations are simply improper subjects for breath testing. DUI criminal defense lawyers are aware that those who have had recent dental work, or who suffer from GERD (gastroesophageal reflux disorder, the medical term for a type of persistent heartburn) are inappropriate subjects for breath testing. There are many other conditions that could cause an unnaturally high reading on a breath test.

Because of the inherent problems with breath testing, anyone arrested for DUI should contact an experienced California criminal defense attorney who is well-versed in these issues. The results of the roadside breath test are often the most damning evidence offered in a DUI case. It is essential that these results be challenged to achieve a successful result.

Evidential Breath Testing & How it Works

Drivers arrested on suspicion of DUI in California are offered the choice of an evidential breath test or a blood test. Motorists arrested for DUI, driving under the influence of drugs are offered a choice between a blood or a urine test. Many drivers choose the evidential breath test and then fear that a drunk driving conviction is inevitable after the test shows a blood alcohol content (BAC) above the legal limit. Luckily, breath tests that show a BAC of .08 percent or greater can be successfully challenged by a skilled defense attorney. The experienced DUI lawyers at The Kavinoky Law Firm can effectively attack breath test results in a drinking and driving case.

Breath machines used in California drunk driving investigations vary from jurisdiction to jurisdiction. The equipment used includes the E-PAS, a hand-held unit that is often administered roadside, or a variety of stationhouse breath-testing machines, such as the Intoxilyzer 5000, the EC/IR, the Draeger, the BAC Datamaster, and many others.

Regardless of the type of machine used, all breath testing in drinking and driving cases is an indirect measurement of BAC. Breath testing devices produce an estimate of BAC through a conversion process. Blood alcohol level is predicted on the basis of certain scientific assumptions, which may or may not be applicable to the person being tested. These scientific assumptions include drivers’ blood/breath partition ratio, their breath temperature, and many other factors.

Since breath testing in DUI investigations always occurs sometime after the accused motorist was actually behind the wheel, which is the relevant time in a drunk driving case, the number only becomes meaningful through a process called retrograde extrapolation. Retrograde extrapolation is an attempt to look back in time and give an opinion about the driver’s alcohol level at the time of driving based upon the breath test results.

This type of speculation is rife with problems. Alcohol levels change over time, and the amount of change depends on many difficult to predict factors. Stomach contents, body weight, gender, the amount of alcohol consumed, the length of the drinking period, elimination or “burn-off” rate, and other personal metabolic factors all interfere with retrograde extrapolation in a DUI investigation.

For retrograde extrapolation to be accurate, the expert must assume that the accused drunk driver is in the “post-absorptive” phase – an assumption not always true since the absorptive phase can last for two hours or more.

There are two types of breath test devices in DUI cases: infrared breath testing machines or fuel cell machines. When using the infrared device, the subject blows into a collection tube. Light passes from one end of the tube to the other, and the machine measures the amount of light beam that is diminished as it passes from one side to the other in the light spectrum of the alcohol molecule.

The fuel cell device testing machine measures the amount of oxidation that occurs on an electromagnetic chip. The amount of electrical charge is converted into a number, which is supposed to represent the driver’s BAC. Both methods of DUI breath testing are subject to many challenges, and a drunk driving criminal defense lawyer knows how to effectively question these results.

Some defense attorneys acknowledge that the BAC reading is correct, but challenge whether the driver was under the influence of alcohol or exceeded the legal limit at the time of driving. Other defense strategies challenge the accuracy of the breath test result itself. A criminal defense drunk driving attorney will typically explore both avenues on behalf of his or her DUI client.

An experienced DUI defense attorney always questions whether the breath test machine was functional. Whether the machine is an Intoxilyzer 3000, Intoxilyzer 5000, Intoxilyzer 8000, EC/IR I or EC/IR II, a Draeger or a BAC Datamaster it must work properly to give reliable results. This means ensuring that the calibration records, usage logs, and maintenance history are all properly documented and don’t reveal any problems.

An experienced California DUI defense lawyer from The Kavinoky Law Firm knows how to investigate potential problems in evidential breath test results. When problems are revealed, it may result in the exclusion of the breath test results  or lessen the weight of the evidence.

How Evidential Breath Tests Work

Evidential breath tests, also known as EBTs, are breath-testing instruments commonly used in California drunk driving investigations. Police and prosecutors rely heavily on EBT results, but they are far from foolproof. A skilled DUI defense attorney from The Kavinoky Law Firm will use a proven strategy to effectively challenge the results of EBTs.

To see how EBTs can be successfully challenged, it’s helpful to understand how alcohol enters a person’s breath. When an individual takes a drink, the alcohol isn’t digested like other substances; It gets absorbed by the stomach and small intestine. From this point, the alcohol enters the bloodstream.

The alcohol is then distributed by the blood to all tissues and organs that contain water. Veins carry the blood to and through the lungs where the blood becomes oxygenated. The lungs are made up of air pockets, which are surrounded by blood-rich membranes thus exposing the lung tissue to the consumed alcohol.

Third, the alcohol is eliminated by the body in the breath by evaporation. Evaporation occurs because the alcohol circulating in the blood comes in contact with the blood-rich membranes in the lung tissue and evaporates. During exhalation, the air is forced out of the lungs and emerges into the breath.

Infrared breath testing instruments identify ethyl alcohol molecules based on the way they absorb infrared light. No other compound absorbs radiation at the exact same wavelengths. In this sense, ethyl alcohol has a distinctive fingerprint.

EBTs measure the amount of alcohol in the breath by a partition ratio and converts it to an estimation of blood alcohol content. The problem with EBTs is that they generally contain instruments that detect the presence of mouth alcohol, commonly referred to as “slope detectors.” Mouth alcohol is the undetected, raw, unabsorbed alcohol in the mouth that falsely elevates the results of the breath test. The sources of mouth alcohol may include:

  • A substance ingested prior to the breath test, like mouthwash, breath strips, cough drops or syrups, or asthma inhalers
  • A substance regurgitated or burped from the stomach
  • A case of gastroesophageal reflux, also known as GERD
  • Dental work, such as dentures, braces, or bridges which trap alcohol
  • Mouth jewelry, such as tongue piercings, which trap alcohol
  • Food in the teeth, especially bread and products containing yeast
  • Tobacco products

The EBT slope detector reflects a real-time reading of the breath sample. Mouth alcohol creates a different pattern than a normal breath sample. If a subject has no mouth alcohol, the EBT device will read a continuous, though not linear, rise in breath alcohol until it reaches a plateau. If mouth alcohol is present, there may be a significant and sudden drop. A slope detector identifies and reports this drop as mouth alcohol, thus invalidating the result.

Another problem with EBTs is that police don’t always follow the proper waiting period before starting the test. Mouth alcohol evaporates after a 15-minute period, as long as no additional alcohol is introduced. Thus, police agencies are mandated to continuously observe the subject for 15 minutes before giving the breath test. This observation period reduces the possibility of a contaminated sample producing a falsely high BAC result.

Another issue with EBTs is California’s implied consent statute. According to the California Vehicle Code, a person who drives a motor vehicle is deemed to have given his or her consent to chemical testing of his or her blood or breath for the purpose of determining the alcoholic content of his or her blood if lawfully arrested for an offense committed in violation of Section 23140 (DUI for those under 21 years of age) or 23152 (DUI ) or 23153 (DUI with injury). That means that a driver is only required to consent to a chemical test if arrested. However, police often administer breath tests prior to making an arrest.

Generally, a person has the choice of either a blood or breath test. However, if drugs are suspected, the person may have to submit to a blood or urine test. But if only one type of test is available, then the person must submit to the available test. For example, if the person in transported to the hospital, they may have to undergo the blood test because no breath testing machines are present at that location.

Further, according to the California Vehicle Code, the person must be told that failing to submit to a chemical test will result in a fine, suspension, or revocation of driving privileges, and mandatory imprisonment.

Finally, if only a breath test is chosen, the driver must be given the choice of having a blood test done in order to retain a sample for independent testing later on, because the breath test does not retain a sample.

Because of the many variables present in EBTs and the regulations governing their use, it is possible to challenge test results in a drunk driving case. Any driver who took a breath test and is facing charges of drinking and driving should consult with a qualified California attorney who specializes in DUI defense.

Blood Testing

Drivers arrested on suspicion of DUI in California must take a breath or blood test to determine the motorist’s blood alcohol content (BAC). Although police and prosecutors consider blood tests to be definitive evidence in drunk driving cases, these tests are open to interpretation. A skilled attorney from The Kavinoky Law Firm who focuses on driving under the influence cases has the experience needed to effectively challenge blood test results.

California’s Implied Consent Law dictates that anyone who drives in the state agrees to take a chemical test if arrested on suspicion of drinking and driving. If a driver is suspected of driving under the influence of drugs (DUI), a blood or urine test may be required.

If the driver refuses to submit to a chemical test, a number of serious repercussions follow, including fines, mandatory imprisonment if the person is convicted of DUI, and DMV suspension of the person’s driver’s license. If the driver refuses a chemical test, the courts have ruled that police have the right to take the defendant’s blood by force. Therefore, submitting to the chemical test is in the best interests of someone arrested for DUI.

When a driver opts to take a breath test, the officer must advise the person of the right to take a blood test in order to retain a sample of blood for later testing by an independent forensic toxicologist. Tests are fallible, and human error is not uncommon.

Improper blood-drawing procedures are a common error in blood-testing. When drawing a blood sample for a drunk driving case, the blood should be drawn into a glass tube that contains a white powder in the bottom; the white powder is a mixture of preservative and anticoagulant. If the level of preservative is incorrect, the blood sample can actually ferment and create additional alcohol. If the sample does not contain enough anticoagulant, the blood will clot, reflecting an artificially high blood alcohol level. Independent testing can reveal such instances. Thus, it may be to the DUI defendant’s advantage to have his or her blood sample independently tested.

The blood must also be drawn by a person certified to perform the draw. The driver’s arm should be cleaned with an alcohol-free wipe. Once drawn, the blood sample must be shaken in order to thoroughly distribute the anti-coagulant and preservative. The sample should be stored in a controlled environment in order to preserve the quality of the sample. Therefore, when defending a drunk driving case it’s important to identify the “chain of custody” in order to fully understand who had access to the sample, when, and how it was stored.

Even when the blood sample is properly collected and stored, the result doesn’t necessarily mean the driver is guilty of DUI. While chemical testing may be accurate in determining blood or breath alcohol content at the time of testing, it is not conclusive evidence of BAC at the time of driving. It is not illegal to be above the legal limit while in a police station. The offense is driving under the influence, not having a BAC above the legal limit at a later time. Because alcohol levels change over time, this is a critical point to understand.

Ultimately, blood tests and other chemical test results can be successfully challenged in court. When it comes to issues of blood-testing in a drinking and driving case, it’s important to have a California lawyer who specializes in DUI defense on your side.

Urine Testing

Drivers arrested on suspicion of DUI in California are required by law to take a chemical test to measure blood alcohol content (BAC). Drivers suspected of being under the influence of alcohol are given a choice between a blood or a breath test. Drivers believed to be under the influence of drugs must take a blood or a urine test.

Urine tests are considered the least reliable of the three types of chemical tests available. Fortunately, urine tests can be effectively challenged in drunk driving or driving under the influence of drugs (DUI) cases. The experienced defense lawyers at The Kavinoky Law Firm know the inherent flaws in urine tests and will use that knowledge to craft an aggressive defense strategy.

Urine tests are typically implemented only when a motorist is suspected of driving under the influence of alcohol and/or drugs. However, urine tests may be given in drunk driving cases when breath or blood tests are not available.

California law dictates that if a urine test is given, the individual must be provided enough privacy to maintain dignity while still ensuring the accuracy of the sample. When the urine test is requested, drivers are advised to empty their bladders, wait 20 minutes, and then go again.

Urine tests have strict protocols but are prone to human error. Police and technicians routinely fail to follow the required procedures, making test results unreliable.

Urine testing is the least reliable method of testing for blood alcohol content. Because the test involves water rather than blood, the result is usually inflated. The concentration of alcohol in the urine is approximately 1.33 times the concentration of alcohol in the blood at the same time.

Urine tests are equally unreliable in DUI cases because it’s impossible to determine when a drug was used. They can only detect metabolites, or inactive leftover traces of a drug. For example, a driver who smoked marijuana on a Friday night could test positive the following Tuesday, long after the drug has ceased to have any effect. Obviously, what a driver did on Friday has nothing to do with his or her fitness to drive on Tuesday.

The flaws inherent in urine testing for drugs have been scientifically documented. A study performed by the National Institute of Drug Abuse found that 20 percent of the labs surveyed mistakenly reported the presence of illegal drugs in drug-free urine samples.

Urinalysis also tends to confuse similar chemical compounds. For example, codeine and non-narcotic cough syrup have been known to produce positive results for heroin. By the same token, Advil has produced false positives for marijuana, and Nyquil for amphetamines.

Urine testing is extremely unreliable in both drunk driving and DUI cases, so it’s possible to effectively challenge the test results. A California lawyer with experience fighting chemical testing can attack the integrity of urine tests and effectively fight a drinking and driving or driving under the influence of drugs charge.