How Does a Breathalyzer Test Work?
Breathalyzer tests are essentially devices that measure the amount of alcohol in a person’s breath. They operate on the premise that, when a person ingests alcohol, that alcohol enters the bloodstream and is transferred to the lungs. How this occurs is that the blood vessel (capillaries) that feed into the lungs collect alcohol in the blood and transfer it to the air inside the lungs where it is exhaled in the breath. This is called diffusion. In very crude terms, the amount of alcohol that makes it from the blood to the lungs is measureable and can be converted to a blood alcohol concentration.
In practical terms, an individual with a specific BAC could theoretically have a specific concentration of alcohol in their blood stream. So, if it was possible to take a sample of a person’s blood and analyze them for their BAC through forensic analysis on the sample, you would arrive at BAC that will theoretically reflect on the breathalyzer if one was conducted immediately after the blood draw. Or at least that is how it would work in a perfect world.
However, there are two shortcomings with that theory. First, not every molecule of alcohol that travels through the blood is going to migrate through the capillary vessels into the alveoli (air sacks) of the lungs and be expelled in the breath . Second, not every molecule of alcohol that is expelled from the lungs exits in the breath. The biological mechanisms at work during the process are too complex to lend reliability to one or another method of measuring. Consequently, numerous factors have to be taken into consideration when measuring breath alcohol concentrations through the use of breathalyzers. These include the following:
As such, breath analysis through the use of a breathalyzer can produce highly unreliable results. Law enforcement officers carry portable, hand-held breathalyzers with them at all times to conduct preliminary breath tests (PBTs) on individuals suspected of driving under the influence of alcohol. PBTs are merely to screen for the possible presence of alcohol. They are not reliable enough to determine whether a person should be arrested or not. At the police department, officers typically have access to BrAC data from an intoxilyzer, wherein samples of a persons breath are collected and form a more reliable testing mechanism for BAC.
From the foregoing, it should now be apparent that BAC should not be used as an absolute index of impairment as that index may be distorted by typical process listed above. For this reason, the effects of alcohol on any particular individual should always be given primary consideration in determining whether or not that person is impaired.
Legal Considerations for Test Admission
In general, a breath test may be used in court to pursue a DWI/DUI case if there has been a legal arrest and subject has provided a sufficient breath sample of adequate quality. The National Highway Safety Administration has provided standard practices for the use of breath test devices (intended to standardize breath tests across the country), and each state has their own regulations incorporating the NHTSA recommendations or detailing the practices as specified by the state. These regulations are designed to ensure that only valid test data is presented to the courts. Based on these requirements, the general requirements for admissibility of the results of a properly done breath test are:
- Legal arrest
- Sufficient amount of breath
- Adequate breath quality
- Sufficient breath test frequency
- Satisfactory standards of device calibration
- Satisfactory standards of device maintenance
- Operator follows the state’s approved procedures and standards
- Breath test is not subject to any other admissibility issue (such as due process violations, enforcement of highway regulations without seeking a search warrant under certain conditions, or improper corporate rule)
The breath test operator is most often also the arresting officer. He is frequently trained sufficiently in the operation of the instrument to operate it during the arrest process, and his subsequent testimony can be supported by the certification records, maintenance records, and calibration records that are likely to be kept at a central location for such devices. The breath test operator must be an individual who possesses knowledge, training and experience to administer the breath test in accordance with state regulations. In New Jersey, for example, the operator must have two weeks of classroom instruction, four hours of simulator instruction, and two weeks of field instruction.
Factors that Challenge Breathalyzer Data
Many legal challenges have been raised regarding alcohol breath test evidence. The results of breath tests can be challenged on various legal grounds, such as instrument malfunction, human error, or the effects of different substances.
Instrument malfunction or improper maintenance can cause inaccurate blood alcohol concentration (BAC) readings. If the device has not been properly tested for accuracy, the results can be thrown out or challenged in court. Calibration is required only on a quarterly basis, even though it is a major factor in reliability. Charged individuals and their attorneys should ask for calibration records when requesting evidence from law enforcement agencies. In addition, complexities in software and hardware require credentialed manufacturers to calibrate devices under tight controls. Yet, forensic labs often lack properly credentialed personnel, as well as proper certification, accreditation, and validation of software and hardware, and certifications are often 20 years old.
Human error can also affect breath test results. Inexperienced law enforcement officers can make mistakes. In some cases, officers fail to follow their own procedures and state regulations. Some failures to follow regulations include failure to wait for a subject to "clear," or failure to give a subject a second test complete with observing the time of the test. In many cases, officers fail to observe subjects for 15 full minutes, as they are required to do. While they may say they did, the video shows otherwise. Some departments have taken this problem so seriously that they no longer allow officers to administer breath tests.
There are external factors that influence BAC test results, even if the devices are functioning correctly. For example, an individual with GERD may have a BAC reading that is as much as five times the actual amount; the fumes in the esophagus can inflame the tissue and create an accurate measurement of the vapors in the stomach, which can raise BAC levels significantly. Individuals suffering from acid reflux in any form can have falsely elevated BAC readings without regard to how much alcohol was consumed. The stomach and tissues produce alcohol when it burns and breaks down. Test devices measure alcohol in the breath and not just what the body has already absorbed from the stomach. In addition, sample replacement, sample switching, and deliberate error all occur at police departments and forensic labs that administer tests.
Recent Court Cases and Precedents
Recently, there has been a continued wave and influx of rulings on this issue in state courts, federal courts, and administrative agencies/chambers. These precedents set the standard for the admissibility of breathalyzer results. For example, early in 2011, the Supreme Court of Pennsylvania ruled in Commonwealth v. Beaman that breathalyzer readings had to be preceded by a BAC DataMaster certification that was not past its expiration date.
At the same time, the Ohio Court of Appeals found that testimony from a "breath testing administrator" was not sufficient proof that the operator was certified in accordance with O.R.C. § 4511.19 (A) (1) (b).
Furthermore, the California Court of Appeal ruled in People v. Alcala (1992) that a defendant could attach a certification or calibration for a breathalyzer that was different than the instrument used on the day of arrest. The court found that the defense did not have to provide a calibration statement for that particular breath test machine in order for the results to be admissible as evidence. This particular ruling referred back to People v. McCarty (1992), where the court ruled that the state must show that the testing device meets the standards set by the National Highway Traffic Safety Administration (NHTSA). The court also alluded to the fact that there might be other alternative methods of qualifying the results of the breath test, even if they should be proven for each individual device. That alternative would be using an NHTSA method to ensure accuracy, as set the standards for the testing of each particular breath testing device.
Most recently, in Commonwealth v. Vargas, the Supreme Court of Massachusetts ruled that "recent scientific information" called the validity of breath tests into question. Due to this scientific discovery, the court threw out the testing results that were presented to the jury in a drunken driving trial.
State Laws Regarding Breathalyzer Readings
Not all states treat breathalyzer admissibility in the same way. While some states follow the same protocol as other evidence, others have different standards, and still others do not permit breathalyzer tests at all. In Arizona, for instance, state law – specifically, 28-1385(C) – requires that breath tests be conducted in accordance with the current rules recommended by the director of the state’s Department of Health Services, in conjunction with the governor-appointed Governor’s Council on Impaired Driver’s. In Tennessee, breath tests must be conducted according to strict procedures and the state legislature reviews the testing instruments that are to be used. Illinois, by contrast, does not give the state authority over the methods by which police officers gather and maintain evidence, including blood and breath samples.
In other words, whether or not a defense attorney can argue the breath test should be suppressed depends on the state where the case is being tried . This can lead to inconsistencies both within a state and between states. For example, Georgia allows breath tests as evidence in a trial but doesn’t have an implied consent law. Illinois, meanwhile, does not normally permit breath tests as evidence in a trial but has an implied consent law. Louisiana doesn’t have a stated implied consent law and only allows breath tests to be administered if refusal might result in license suspension.
When exactly is the breath test used after a DUI arrest? In some states, if a driver refuses to submit to a breath test, it’s considered a crime. In states like Iowa and Maine, implied consent laws state that the driver consents to provide a sample when applying for a driver’s license, making it a crime to refuse to provide one. In Idaho, on the other hand, even though driving a vehicle is expressed consent, a driver can’t be charged with a crime for refusing to submit to a breath test.
Breathalyzer Tests versus Blood Tests
In spite of their drawbacks, breathalyzer tests are much more common than blood tests in DUI cases. Police officers simply believe these tests are more accurate.
In fact, people were quick to adopt these tests because they are easy to administer. A blood draw takes time, can be very uncomfortable for the suspect, and requires a second officer’s help, along with special licensing. If the officers wait for a blood draw, they are forced to release the suspect on bond or risk having to get a warrant to take the blood.
However, police have the luxury of keeping someone in custody until they get authorization to enter a blood draw room with an officer who has proper licensing.
Additionally, many breathalyzer manufacturers do not allow police to create a data dump to determine if the machine is working properly, which may be one good reason for excluding breath test results from trial, since the defense was not able to see the data. In fact, the Brennaman case in 2007 was reversed at trial for precisely that reason. The Susquehanna County District Attorney was not allowed to see the data from the Intoxilyzer 8000, which was not even manufactured by Intoximeter Corporation.
Judge Brennan correctly observed in his decision that this information is of critical importance in determining whether the machine was working properly. On remand, the trial court had his work cut out for him. In addition to reviewing the operation of the machine, the Commonwealth had to show that the defendants’ blood alcohol levels were elevated at the time of the car accident.
Lawyers learned the hard way over the years that they had to go to court and fight on behalf of their clients long before the final hearing. With a good motion to suppress or for other pretrial matters, the Harrisburg DUI attorney could ask for an evidentiary hearing to determine the following:
- the lack of proper installations
- improper calibration
- improper use in the field
If the machine is not properly calibrated, the reading will not be admissible as evidence in court. The issue has nothing to do with how the machine is used in the field. For example, a police officer uses a straw to blow into the machine and gather the person’s breath sample. Afterward, he blows on another straw to clear the air away from the machine. If the machine is not cleaned, it cannot measure the result properly and the blood alcohol level will be questionable.
In any event, even if the court is willing to allow the breathalyzer test to stand, the judge will allow the jurors to question the accuracy of the machine.
How to Safeguard Your Rights In a DUI
How does someone protect themselves from a potentially false DUI charge? We touched on the steps for fighting DUI charges earlier in the article, but there’s more you can do to maintain your rights. All drivers have a legal right to speak to an attorney before submitting to a breathalyzer test. An officer may request you take a field sobriety test after you commit a suspected DUI offense. For example, if an officer pulled you over for reckless driving, they might ask that you submit to a breathalyzer test to supplement their drunk driving suspicions. In many cases, it might be easier and quicker for you to submit to this request than to argue with the officer. However, you need to know that you can opt to refuse it. The reason you may refuse the test is because it may be inaccurate. The officer asked so you could blow a .08 reading or over. However, there are factors that could create inaccurate readings due to breathing patterns or other physiological differences of the person taking the test . Immediately after consuming alcohol and before producing a sample for a breathalyzer test, alcohol levels in the quasi gas form of its metabolism are much higher than those in your blood. If you’ve recently taken alcohol, it may still be fresh on your breath and therefore detectable with a breathalyzer test. In addition, although a breathalyzer test is designed to provide an accurate result, it can be thrown off by poor calibration or other software problems within the device. You should be aware that your own police department has to ensure that their breathalyzer devices and utilization procedures are up to par. Should you suspect that this equipment or practices were not satisfactory, you should immediately obtain the advice of a qualified attorney who specializes in DUI. This may be a way to get the court to deem the breathalyzer test results inadmissible in court.