Many drivers arrested for DUI / DWI 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 / DUI cases has the skills needed to effectively challenge PAS tests in driving under the influence cases.

DUI / DWI 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 / DWI trial was that the PAS machine indicated the presence of alcohol – the numeric results were excluded.

Unfortunately, that is no longer true. Courts hearing DUI / DWI 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, which are merely screening tests given to support the officer’s decision to make an arrest, and roadside evidential tests. 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 / DWI 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 / DWI investigations even more complicated. These versions of the roadside breath test are the evidential test that is required under the Implied Consent Law. The exact same machine is used to administer this mandatory test as is used for what 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 / DWI 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) which begin with a one-year driver’s license suspension, with no opportunity for a restricted or provisional license during that year.

Roadside breath testing arose to address a significant issue in drunk driving prosecutions – because of the typical time-lapse between driving and testing, there was often an issue of whether the driver’s BAC could have been below the legal limit at the time of driving. The aim of roadside breath testing in drunk driving cases was 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 any advances made. The challenges to both the PAS test – the 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 / DWI 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 / DWI 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 stationhouse 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, and 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 are being misinterpreted as alcohol, and delivering 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 / DWI cases, and especially in cases 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 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 / DWI 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 / DWI 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 / DWI case. It is essential that these results be challenged to achieve a successful result.

Police in California sometimes use sobriety checkpoints – temporary roadblocks on public streets or roadways designed to snare drunk drivers. Over the years, courts have established strict protocol to govern the operation of sobriety checkpoints – guidelines that police don’t always follow. The experienced DUI / DWI defense lawyers at The Kavinoky Law Firm are well-versed in the requirements of sobriety checkpoints and can determine whether a drunk driving arrest made at a Sobriety Checkpoint was valid.

Many of the requirements governing sobriety checkpoints were created by the landmark U.S. Supreme Court case of Michigan Department of State Police vs. Sitz. The Court’s ruling attempts to balance the rights of drivers against the interests of society in keeping impaired drivers off the road.

Police must select vehicles using a neutral mathematical formula, and the checkpoints must be maintained safely for both police and motorists, have high visibility, and minimize the average time each motorist is detained.

Each driver should be stopped only long enough for an officer to ask a few brief questions and to look for signs of intoxication, such as alcohol on the breath, slurred speech, and glassy or bloodshot eyes. If the driver shows no signs of impairment, he or she should be permitted to drive away without delay. If the officer does spot signs of intoxication, the driver can be sent to a separate area for a field sobriety test. At that point, further investigation must be based on probable cause, and general principles of detention and arrest would apply.

The sobriety roadblock should be part of an ongoing safe-driving program, and must conform to an established departmental policy. A supervising judge and a representative of the district attorney’s office should participate in the planning. The checkpoint’s supervising officers must be well-versed in the safety and civil rights issues surrounding such an operation. The roadblock should be announced to the public in advance through the media.

The Supreme Court deemed that the main purpose of a sobriety checkpoint is not to discover evidence, crimes or to arrest drunk drivers, but to promote public safety by deterring drunk drivers from endangering the public. Thus, a sobriety checkpoint roadblock serves a regulatory purpose and is not considered a criminal investigation roadblock, and no warrant is required.

The Supreme Court has held that stopping a vehicle at a sobriety checkpoint constitutes a seizure under the Fourth Amendment. A Fourth Amendment seizure occurs “when there is a governmental termination of freedom of movement through means intentionally applied.”

The key question when considering a Fourth Amendment seizure is reasonableness. The courts have ruled that not all roadblocks violate a motorist’s Fourth Amendment right against unreasonable search and seizures. In order to determine whether there has been a Fourth Amendment violation, courts apply a balancing test which weighs the government’s interests against the intrusiveness of the detention on the individual.

An experienced California DUI / DWI lawyer will evaluate every aspect of the checkpoint to determine whether it meets the guidelines established by the U.S. Supreme Court. If the checkpoint was not operated according to that protocol, a skilled attorney such as those at The Kavinoky Law Firm will argue that any evidence gathered during the stop was improperly obtained, and should be suppressed.

The courts have ruled that sobriety checkpoints don’t violate a motorist’s Fourth Amendment rights if they are conducted within certain criteria. California drunk driving sobriety checkpoints must follow specific guidelines set forth by the U.S. Supreme Court in order to be constitutional. However, police don’t always follow that protocol. If they don’t, any evidence gathered as a result of an arrest at a sobriety checkpoint may be suppressed at trial.

The skilled DUI / DWI defense attorneys of The Kavinoky Law Firm are extremely knowledgeable about the requirements of California drunk driving Sobriety Checkpoints and can determine whether an arrest was valid. They will request the following information during pre-trial discovery to help determine whether police followed the established guidelines:

• The identity of all involved law enforcement personnel, both sworn and civilian
• The identity of each person arrested at the roadblock. This information is necessary to determine whether proper procedures were actually followed, if defense counsel opts to interview them
• Where field sobriety tests were performed, and who conducted them
• Where chemical tests were given, and who conducted them
• All communication, diagrams, and reports used in designing the roadblock
• How long each driver was stopped at the checkpoint
• Whether a neutral formula was employed in stopping motorists, or whether officers used their own discretion
• Whether the roadblock had an official appearance, including warning signs, lights, and uniformed personnel
• How the location of the roadblock was determined
• How the timing and duration of the roadblock was determined
• Whether the public received advance notice of the checkpoint
• Whether the safety of drivers was of primary concern
• Whether motorists were allowed the opportunity to turn away from the roadblock without being detained

An experienced California defense lawyer will analyze this information to determine whether there were discrepancies between the protocol set by the courts and the operation of the checkpoint. If police did not follow all of the necessary guidelines, and there was no probable cause for a stop, a DUI / DWI defense attorney will move to have all of the evidence that stemmed from the arrest excluded.

If police don’t follow the established guidelines when operating a sobriety checkpoint, probable cause is needed to make an arrest if there is no warrant. Probable cause exists when the facts known to the officer would lead a person of ordinary care and prudence to believe that the person is guilty of a crime. The officer must be able to articulate why the driver was stopped and ordered to exit the vehicle.

Probable cause must exist during each stage of the encounter, including the performance of the field sobriety tests, chemical testing, and the arrest itself. If there was no probable cause, and the search and seizure took place without a warrant, there is a strong likelihood that the court will grant the motion to suppress, thus excluding the evidence gathered during the sobriety checkpoint.

This type of challenge can result in the exclusion of evidence that includes field sobriety tests, statements made by the defendant, and the results of any chemical tests. Roadblock sobriety testing is considered a search under the Fourth Amendment, and chemical tests of breath, blood, or urine are firmly established to be a seizure for Fourth Amendment purposes.

An experienced DUI / DWI defense attorney will argue that without a warrant or probable cause, all of this evidence must be suppressed. The prosecutor then bears the burden of proving that the search of the defendant and the seizure of the sample were the product of a lawful arrest.

Even though sobriety checkpoints have been sanctioned by the courts, not all drunk driving checkpoints are conducted according to established guidelines. Ultimately, evidence obtained at an improperly conducted sobriety checkpoint can be challenged. The first step is to consult with a California lawyer who concentrates on drunk driving defense.

When conducting sobriety checkpoints, police must follow strict guidelines outlined by the California Supreme Court in the landmark case Ingersoll vs. Palmer. If police do not follow the criteria laid out in Ingersoll, the DUI / DWI roadblock isn’t lawful, and any evidence gathered during a drunk driving arrest may not be admissible in court. The skilled DUI / DWI defense lawyers from The Kavinoky Law Firm can determine whether a sobriety checkpoint was conducted lawfully.

In the Ingersoll decision, the Court outlined eight (8) requirements designed to minimize the intrusiveness on the individual and balance the needs of society to keep drunk drivers off the road.

According to Ingersoll, supervisory police officers, not officers in the field, must make decisions about the establishment and location of sobriety checkpoints. This is important to reduce the potential for arbitrary and random enforcement.

The Court’s decision also limited the discretion of police to stop drivers at checkpoints. Police should use a neutral mathematical formula, such as every third, fifth, or tenth driver, to determine which vehicles to stop. This requirement takes away the discretion of the individual officer to choose to stop drivers based on appearance.

Maintaining safety for motorists and officers must be a primary consideration. Proper lighting, warning signs and signals, and clearly identifiable official vehicles and personnel are required. The checkpoint should only be operated when the traffic volume allows the operation to be conducted safely.

A supervisory officer must choose a location that will be most effective in actually stopping drunk drivers, such as roads which have a high incidence of alcohol-related accidents and arrests.

The time and duration of DUI / DWI roadblocks also must be considered. Police must use good judgment in scheduling sobriety checkpoints, with an eye to effectiveness of the operation, and with the safety of motorists in mind. So long as these considerations are in effect, there are no specific rules about the timing or duration of the roadblock.

Sobriety checkpoints also must be highly visible so that drivers can easily see the nature of the roadblock. Flashing warning lights, adequate lighting, police vehicles, and the presence of uniformed officers all contribute to visibility. Not only are such factors important for safety reasons, but advance warning will reassure motorists that the stop is duly authorized.

Each driver should be stopped only long enough for the officer to question the driver briefly and to look for signs of intoxication, such as slurred speech, alcohol on the breath, and glassy or bloodshot eyes. If the driver doesn’t show any signs of impairment, he or she should be permitted to drive on without further delay. If the officer does observe signs of impairment, the driver may be directed to a separate area for a field sobriety test. At that point, probable cause must propel any additional investigation, and general principles of detention and arrest would apply.

The public should be informed in advance about sobriety checkpoints, although police are not required to disclose its specific location. Publicity both reduces the intrusiveness of the stop and increases the deterrent effect of the roadblock. Advance notice is intended to limit the intrusion upon the individual’s personal dignity and security because those stopped would anticipate and understand what was happening. Further, advance publicity serves to establish the legitimacy of roadblocks in the minds of motorists.

Drivers who take steps to avoid a roadblock cannot be stopped merely because they attempted to avoid the checkpoint. However, if the driver commits a vehicle code violation or displays obvious signs of intoxication, there is adequate probable cause to pull over the motorist, after which point general principles of detention and arrest apply.

The California Supreme Court’s Ingersoll decision gave police latitude in conducting sobriety checkpoints, but it also established guidelines under which the roadblocks must be operated. If police don’t follow that protocol, the evidence gathered as a result of the roadblock may be suppressed as a violation of the driver’s Fourth Amendment rights. A California DUI / DWI lawyer who is well-versed in the requirements of sobriety checkpoints can determine whether a roadblock was lawfully executed, and whether any evidence gathered is likely to be suppressed.

Drivers arrested for DUI / DWI at sobriety checkpoints in California often ask why police are allowed to stop them without probable cause. The answer may come as a surprise – the courts have ruled that probable cause isn’t needed when police operate sobriety checkpoints, as long as certain criteria are followed. However, police don’t always follow those guidelines. An experienced DUI / DWI defense lawyer from The Kavinoky Law Firm will determine whether police followed established protocol while conducting a sobriety checkpoint.

Stopping a vehicle at a roadblock is considered a seizure for Fourth Amendment purposes. The Fourth Amendment states that individuals should be free from unreasonable searches and seizures of their person and their belongings. The key factor in Fourth Amendment issues is reasonableness. The officer must have reasonable suspicion that a crime has occurred, or the seizure must be carried out under a plan containing explicit, neutral limitations on the conduct of individual officers.

California’s constitutional principles are based on the same issues. The government’s interests is weighed against the intrusiveness of the detention to determine reasonableness. In California, there must be probable cause in order to justify an investigative stop or detention without a warrant. Probable cause means the officer must be aware of specific facts that some crime has or will take place, and the person stopped is somehow involved in that activity. Reasonableness requires that anyone else in the officer’s position would have reached the same conclusion.

However, not every search and seizure requires a reasonable suspicion of criminal activity. Searches that are done to pursue an administrative purpose instead of as part of a criminal investigation may be permissible under the Fourth Amendment, even without probable cause. When evaluating an administrative screening, reasonableness is determined by balancing the public interest against the intrusion on the individual. Therefore, some types of roadblocks, such as sobriety checkpoints, are legal, while others are not.

Drunk driving roadblocks are considered to be part of a regulatory scheme with an administrative purpose, and not traditional criminal investigative stops. The primary purpose of a sobriety roadblock is to promote public safety by keeping drunk drivers off the road.

Therefore, if the appropriate guidelines have been followed, DUI checkpoints are legal and don’t require probable cause. The guidelines are fairly straightforward – there must be a random formula – such as every third or fifth vehicle – which limits the discretion of the officers in deciding who to stop. The intrusiveness on individual drivers must be minimal. Each driver’s detention must be brief, involving just a few brief questions that allow the officer to look for signs of intoxication. In addition, officers may shine their flashlights into the vehicle to look for alcoholic beverages. The Supreme Court has ruled that this intrusion on the individual is slight in comparison to the value to society in keeping drunk drivers off the road.

Drivers have also been arrested on suspicion of DUI / DWI after being stopped at other types of roadblocks unrelated to sobriety checkpoints. Some of these roadblocks are lawful, and some are not.

The Supreme Court has ruled that roadblocks whose primary purpose is to detect evidence of ordinary criminal activity are unconstitutional, and therefore illegal. Roadblocks designed to detect illegal drugs are one example. Illegal drugs aren’t believed to pose the same vehicle-related threat to life and limb that exists with drunk driving. If police were allowed to stop drivers to check for every crime facing society, the constitutional protections we enjoy today would disappear. Therefore, because the primary purpose of a drug roadblock is to detect evidence of ordinary criminal wrongdoing, it is unconstitutional.

However, the Supreme Court has sanctioned roadblocks held to seek information and locate witnesses to a crime as being constitutional. Illinois v Lidster held that an Illinois roadblock did not violate the Fourth Amendment’s prohibition of unreasonable search and seizure.

The roadblock challenged in the Lidster case was deemed reasonable because it advanced a grave public interest and only minimally interfered with Fourth Amendment rights. Police in this case were investigating a death by stopping drivers on the same stretch of road, at the same time that the accident occurred, asking motorists briefly whether they had witnessed the crime or had any information. Because the crime the officers were investigating was motorist-related, and the stop itself was brief, it was considered constitutional.

Some California DUI / DWI arrests that occur at roadblocks are valid, and some are not. A skilled California defense lawyer who focuses on drunk driving cases such as those at The Kavinoky Law Firm can determine whether the roadblock was properly conducted. If the roadblock wasn’t conducted lawfully, any evidence collected likely will be suppressed in court.

Drivers under investigation for DUI / DWI in California are typically given a field sobriety test before being arrested. These physical agility exercises, which are usually given next to a busy freeway or on the street, aren’t tests in the traditional sense, because they’re designed to be failed. Their real purpose is to establish probable cause for a drunk driving arrest and to generate evidence for a court case. However, the skilled attorneys from The Kavinoky Law Firm can effectively challenge field sobriety tests and other evidence in a drunk driving case to create reasonable doubt of the driver’s guilt.

Field sobriety tests fall into two categories: Standardized and Non-standardized. The National Highway Transportation Safety Administration (NHSTA) has standardized three field sobriety tests – the Horizontal Gaze Nystagmus Test, the Walk-and-Turn Test, and the One-leg Stand Test. Because these three tests have been recognized by the NHSTA, they carry more weight in court than non-standardized tests, but a skilled attorney can successfully challenge the results of standardized field sobriety tests in court.

Field sobriety tests reputedly assess the mental and physical impairment caused by alcohol intoxication, but most of the so-called signs and symptoms of alcohol impairment can be traced to physical problems unrelated to alcohol use.

Alcohol causes both mental and physical impairment, but mental impairment always takes place before physical impairment occurs. Physical impairment can be masked by individuals with a high tolerance for alcohol, but mental impairment cannot be disguised. Therefore, if a driver suffers from physical difficulties but no mental impairment, the physical problems were caused by a source other than alcohol.

In order to return a DUI / DWI conviction, every juror must be convinced of the driver’s guilt beyond a reasonable doubt. A skilled attorney knows that the reliance of field sobriety tests on physical agility poses serious problems for prosecutors, and creates reasonable doubt in the minds of jurors.

There are many issues unrelated to alcohol use that can cause physical impairment, such as illness, injury, fatigue, or nervousness. An experienced DUI / DWI defense attorney from The Kavinoky Law Firm will take a complete medical history to determine whether causes other than alcohol may have contributed to any impairment, and use this information to challenge the results of a field sobriety test.

Drivers arrested on suspicion of DUI / DWI 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 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 (DUID) 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 drugs or driving under the influence of alcohol and 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 DUID 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 DUID cases, so it’s possible to effectively challenge the test results. A California lawyer with experience defending DUID and DUI / DWI cases can attack the integrity of urine tests and other types of chemical testing, and can effectively fight a drinking and driving or driving under the influence of drugs charge.

Drivers suspected of DUI / DWI in California often must perform field sobriety tests before being arrested. However, no matter how well the driver does on the tests, a drunk driving arrest is practically inevitable. The test is used solely to establish probable cause and create evidence for a court case. However, a skilled DUI / DWI lawyer from The Kavinoky Law Firm can successfully challenge field sobriety tests.

The Walk-and-Turn Test is one of three field sobriety tests standardized by the National Highway Traffic Safety Administration (NHTSA). Like other field sobriety exercises, the Walk-and-Turn Test is a divided-attention test – it’s designed to detect both mental and physical impairment by forcing the driver to focus on two tasks simultaneously. A prosecutor will use the test results as circumstantial evidence that the driver was impaired by alcohol or drugs.

The Walk-and-Turn Test is administered in two parts. The driver must first stand heel-to-toe with arms down while listening to the instructions. The officer tells the driver to take nine heel-to-toe steps along a real or imaginary line, turn, and return toward the officer in the same way. During the test, the officer will note any signs of impairment displayed by the driver.

The signs of intoxication the officer looks for include an inability to maintain balance during the test instructions, starting the test too soon, pausing while walking, an inability to touch heel to toe, veering off of the line, using the arms to balance, losing balance during the turn or inability to turn correctly, and miscounting the number of steps. If the officer spots two or more of these signs, he or she will assume that the driver has a blood alcohol content (BAC) of .10 percent or greater, and an arrest for DUI / DWI will follow.

However, many of the so-called signs of intoxication watched for in the Walk-and-Turn Test can be caused by physical conditions unrelated to alcohol, such as illness or injury. Alcohol consumption causes both mental and physical impairment, but mental impairment always occurs first. Physical impairment can be disguised by those with a high tolerance for alcohol, but mental impairment cannot be hidden. Therefore, if the driver shows only physical difficulties but no mental impairment, the field sobriety test results can be successfully challenged.

This test is particularly challenging for drivers with back or leg injuries, individuals older than 65, overweight drivers, and people with inner-ear disorders. A driver who performs the test on uneven ground, or who is wearing high heels, also isn’t likely to perform well.

Sometimes the officer doesn’t even conduct the Walk-and-Turn Test properly, or doesn’t correctly interpret the results. A California criminal defense attorney with a proven track record of winning driving under the influence cases can determine whether factors other than alcohol impairment hindered the driver’s test performance, and challenge the results.