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Breath Test Defenses

If you gave a breath test, you should know THE RESULTS ARE NOT 100% ACCURATE. There are many good defenses to breath test cases. Here are some of the defense that might apply to you:

If you gave a breath test at the police station, the police officer would have used the Intoxilyzer 5000en. Attorney Hynes owns this same exact machine and knows its limitations.The officer gave you your breath test tubes. New Hampshire is the only state that still does that. DO NOT OPEN THE BAG & BRING THE BAG TO YOUR LAWYER SO THAT YOU CAN GET THE TUBES INDEPENDENTLY TESTED.


Here are my top 10 Breath Test Defenses

1. It does not actually measure ethanol (drinking alcohol). The machine works by detecting very small amounts of particles that it considers alcohol, using light, based upon their wave - lengths. The problem is the machine is not specific to ethanol /drinking alcohol. It can detect other chemicals on the same wave-length, such as wood alcohol, isopropanol, acetone, and other chemicals.

2. The machine is not 100% accurate and has a margin of error. This is why the DMV will not act on a suspension for a BAC of .08.

3. The machine can be faulty and often breaks, which is why it is important to look at the machine log.

4. The operator may not have been certified.

5. The machine uses what is called a "partition ratio" to determining your BAC (Blood alcohol content) based upon BrAC (Breath alcohol content). The assumption it uses is 2100:1. Put simply, the machine assumes that a certain amount of breath alcohol translates to a certain amount of blood alcohol. The machine does this based upon AVERAGES in humans. However, not everyone has a partition ratio of 2100:1. If your partition ratio is different, which it likely is, your reading will either be too high or too low. Attorney Hynes is able to retain an expert chemist to better explain this to officers, judges, and juries.

6. The machine determines BAC using an assumption of your body temperature. Again, this is an average. If your body temperature was higher at the time, you will give a falsely high reading. This is particularly common for women who are in their pre-mesntrual phase, as their body temperature is usually higher during that time. Odds are pretty good the officer did not give you a thermometer to test your temperature. (I have never heard of an officer doing that, or asking a woman what phase of her cycle she is in).

7. Breathing patterns affect the machine. If you hold your breath, or blow for too long, or hyperventolate, you can be giving false results.

8. Radio frequency interferent RFI (radios, cell phones, etc.) interferes with the machine.

9. The machine will sometimes detect "mouth alcohol", which is different than alcohol from the alveolar air from the lungs lungs, or its blood equivalent. This is why the cop must watch you for 20 minutes prior to the test to see that you don't burp, regurgitate, or put anything in your mouth. Similarly, GERD - Gastroesophageal reflux disease - can give too high of a reading as air from the stomach (reflux) comes into the mouth.

10. Testing during the absorptive phase. The State must prove what your BAC was AT THE TIME OF DRIVING. Often, the breath test is around an hour or so after you were driving. During this time, the alcohol in your blood either increased, decreased, or remained the same. If you drank close in time before driving, the alcohol likely did not absorb into your body/blood at the time you were driving. Accordingly, by the time you gave the test and it did absorb, your reading would be faslely high.


Intoxilyzer 5000


According to the manufacturer (CMI), the Intoxilyzer 5000 is used by more than 20 States. With a one year, up to 3 year manufacturer warranty. (I can almost guarantee you the model used by the department is more than 3 years old, but if you want to check for yourself, there is a date on the back of the Intoxilyzer.

How the Intoxilyzer Works

The Intoxilyzer works using infrared (IR) technology. Meaning, it calculates BAC by light.  Different chemical compoundsabsorb light energy at specific wavelengths.

At one end of the Intoxilyzer sample chamber is a Quartz-Iodide lamp, which directs light through the chamber. The light then passes through a filter wheel onto a Lead Selenide infrared energy detector.

The filter wheel allows only specific wavelengths of light to pass through.  The wheel rotates so that each filter is inserted one at a time. It rotates at around 1,800 revolutions per minute[2]. There is both a 3 filter version, and a 5 filter version[3].  The five filter one checks for microns at 3.80 (reference); 3.52 (toluene); 3.47(ETOH / Ethanol); 3.40 (acetone); and 3.36 (acetaldehyde)[4].  The machine measures a reference point by measuring the amount of infrared energy striking the Lead Selenide. During a breath test, the alcohol vapor in the chamber rises, and the amount of light reaching the detector decreases[5]. A BrAC is obtained by comparing the ratio of microns at the reference, to the ones at the alcohol wavelength. The result is displayed in grams of alcohol per 210 liters of breath (this is also referred to as a partition ratio of 2100:1)[6]. Mouth Piece

The user first blows through a mouth piece (spit trap). There are a few different variants available.

[7] .

Some versions are more accurate than others. The purpose behind the spit trap is to prevent saliva/ other foreign substances from entering the breath tube, and then the machine.Saliva has a different alcoholpartition ratio to blood than breath does.

The officer must replace the mouthpiece between each sample, as well as replacing it if the person attempts to give a sample that the machine does not recognize. The officer has 60 seconds to replace the spit trap between the breath samples[8]. If the officer fails to replace the mouthpiece, alcohol might have been built up from the previous test. Breath Tube

The air being blown then passes through a heated breath tube. The tube is heated to prevent condensation from forming[9]. The tube has an antenna that is supposed to check for RFI (Radio frequency interference). [10] Types of Checks by the Machine

The machine checks ambient air, the subject’s breath, and the simulator solution.

The ambient air check determines how much alcohol is in the air surrounding the mouthpiece. Basically, the machine pulls in the air without anyone blowing into it. The air blank result will always be zero, even if the machine detects alcohol. The machine uses this reference as a starting point. It will only produce an ambient failure result if the result is a 0.10 reading or higher[11]. During the ambient air phase, the screen of the Intoxilyzer does not show the present result as it does while someone is giving a breath sample.

The simulator solution is a predetermined amount of BAC (.10, .20, and .30). It is checked at internal 1,2, and 3 respectively.  After the subject blows and the machine runs another blank, it captures a sample from an external reference (A Guth Model 2100 simulator)[12] Slope Detector

The machine also checks the slope of the result. This means, if the BAC value is changing too rapidly, the machine will consider it mouth alcohol, or some other problem, and not accept the sample. One can check this by putting alcohol in their mouth right before blowing. The result will start off incredibly high, but fall rather quickly. If it falls, or even increase too fast, the machine will not accept the sample.

Generally, the machine will give a continuous tone while it is collecting a sample. However, once there is a 0 to the left of the decimal place in the Dot Matrix display, the machine will consider it a valid result if the person stops blowing. Sometimes, when the slope is low enough at a given time, the 0 both comes and goes away. Accordingly, it is possible to collect a result while the tone is still going, and while the machine is still obtaining a sample and doing calculations. Required Sample Amount

The machine requires the following for a successful sample:

A blow for minimum for one second;

Minimum sustained rate of .15 L/sec;

Minimum volume of 1.1 liters of sample;

Blow until the BrAC change is minimal[13].

Practice Note: If the driver was considered a refusal by the arresting officer but attempted to give a breath test, see if the officer gave any incorrect instructions, such as blow hard quickly, or blow low for a longer amount of time.

11.1.2 Defenses Related to the Accuracy of the Intoxylizer

The State, and even the manufacturer, likes to tout the Intoxilyzer 5000 as very accurate when it comes to trial. However, a simple question to ask is:“if the Intoxilyzer 5000 is so accurate and reliable, why is there an Intoxilyzer 8000?” (The reason the Intoxilyzer 5000en must be used in New Hampshire, is because it is presently the only model of any breath machine that can retain capture sampled tubes). Notice, when the State wanted to upgrade the machines, they noted how there are better machines (presumably more reliable) on the market[14].

"You'd be adding confidence and validity to the test," said Nancy Mobile, supervisor of the lab's breath-testing unit.

"And you'd have greater assurance of the specificity of the alcohol level," said Pifer, Director of the State Police lab.  "But here's a situation where there is a more scientific way to do the testing.

Ann Rice of the state attorney general's office noted there is new, improved technology.”

See Chapter 3.5.9 dealing with defenses related to not complying with statutory guidelines.

Other defenses Include:

“List of physiological variables potentially important in connection with breath-alcohol measurement for legal purposes. Failure to adequately control these biological factors will contribute to the variations in the blood/breath alcohol relationship reported in the literature.

Phase of ethanol metabolism

Arterio-venous differences

Source of blood analyzed; arterial, venous, capillary

Blood hematology; hematocrit value, salt, fat, and protein content

Intra-pulmonary gas pressure

Ambient temperature and humidity

Expired-breath temperature

Breathing pattern; hypo-and hyper-ventilation

Bronchopulmonary disease

Presence of mouth alcohol

Regurgitation of stomach fluids

Phase of exhalation; end expiratory or top-lung air

Breath specimen; rebreathed, end-expired, mixed expired

Body temperature; hyperthermia-hypothermia[15]



Margin of error

No machine is 100% accurate. It is an inherent margin of error.


Partition Ratio

A partition ratio is a fancy way of saving it is a formula to convert breath alcohol concentration to blood alcohol concentration. Any number used is typically an average of different people. One of the leading blood scientists has held: “Obviously, there cannot exist a universal fixed blood/breath ratio of ethanol which applies for all subjects under all conditions of testing.[1]

Besides everyone having a different ratio, decreased lung capacity/shallow breaths can affect the results by as much as 50%[2].

[1]Jones at 14.

[2]Booth v. Director of Revenue, 34 SW 3d 221,223 (2000).


Temperature of your breath

A fever, or a woman’s menstrual cycle/menopause, can give higher than average body temperatures. Arguably, if someone is stressed, such as due to an arrest, their body temperature will also rise. When the body’s fight/ flight system is activated the muscles tense, heart rate and thevital organs speed up and as a result, blood flow is shunted from the extremities and directed to the vital organs to facilitate the increased level of arousal. As a result, changes of 5°, 10°or 15° can occur within just a few minutes[1]. If the officer says the person has a flushed face, you may also be able to argue an increase in body temperature.

Breathing Pattern

Similarly, breathing pattern can affect the BAC calculations. The subject's manner and mode of breathing just prior to providing a breath sample for analysis can significantly alter the concentration of alcohol in the resulting exhalation. A driver holding his breath for a short time (20 seconds) before exhalation can increase the alcohol concentration in exhaled air by 15%. Alternatively, hyperventaliting, lowers it up by to 20%[1].

As breath is expired from the lungs, the longer the person breaths, the higher the temperature of breath is. “The temperature of breath as it leaves the mouth rises from about 33.3 to 34.4°C as the volume of breath exhaled rises from 500 to 4500 ml”[2]. Accordingly, the person’s BAC should always be going up as the person continues to blow into the machine. If the officer says “blow, blow, blow”, he can artificially inflate the BAC, because the Intoxilyzer does not compensate for breath temperature, or use it as part of its calculations.

[1]Jones at 18

[2]Jones at 17


Mouth Alcohol

To get a valid BAC, the machine must know the alcohol concentration in your lungs. Alcohol in your mouth will not affect your BAC as the alcohol did not absorb into your blood. Mouth alcohol will always give a falsely high reading.

[1]People v. Bonutti, 788 NE 2d 331, 334(2003)

[2]Barone at 2-62.


GERD / Acid Reflux Disease

Similar to Mouth alcohol is Gastroesophageal reflux disease (GERD). Reflux means the stomach acids and other contents go back up through the esophagus into the throat and mouth. In healthy people the lower esophageal sphincter closes. In patients with GERD it does not. Alcohol, beer, wine, coffee, and drinks with carbonation can make the symptoms of GERD worse because they dilate the stomach and therefore dilate the lower esophageal sphincter[1].

Air from the stomach, is not the same as “deep lung air.”Accordingly, the result will be inaccurate. Because a person with GERD can have a constant flow of air, the slope detector will not notice the problem, as opposed to a spike by a burp.

One can be tested for GERD with an endoscopy. The photographs can be looked at to see if there is evidence of damage caused from the acid erupting. Further, photographs can determine if the Lower Esophageal Sphincter is open[2].

If you take medicine for acid reflux, this can also help to show you have GERD

[1]People v. Bonutti, 788 NE 2d 331, 334(2003)

[2]Barone at 2-62.


Operator Error

Even though the officer has training, they sometimes make mistakes in administering a breath test.


Testing During the Absorptive Phase

The absorptive phase is when alcohol is still being absorbed by the body from the stomach. All BAC levels will be inaccurate (in all likelihood higher) if the person is tested in the post-absorptive phase if he was in the absorptive phase at the time of driving. Studies by Kurt M. Dubowski indicate varying ranges of elapsed time from the end of alcohol intake to peak blood alcohol concentration of 14 to 138 minutes, 9 to 114 minutes, and 12 to 166 minutes[1]. He concludes:

“It is often impossible to determine whether the postabsorptive state has been reached at any given time. Those factors make it impossible or infeasible to convert the alcohol concentration of breath or urine to the simultaneous blood alcohol concentration with forensically acceptable certainty, especially under per se or absolute alcohol concentration laws.

However, specific to breath tests, “During the absorption phase and around the peak BAC breath analysis tends to overestimate venous BAC and the differences will depend on the actual blood/breath ratio for the person tested in comparison with the 2100 calibration factor and the magnitude of arterio-venous difference[3]One study showed a breath test result can be as much as 100 percent higher than the BAC level during the absorptive phase[4].

[1]Kurt M. Dubowski, Absorption, Distribution and Elimination of Alcohol:Highway Safety Aspects, 10 J. Stud. Alcohol Suppl. 98-105 (July 1985).

[2]Id. at 105

[3]Jones at 17

[4]E. Martin, W. Moll, P. Schmid, L. Dettli, The Pharmacokinetics of Alcohol in Human Breath, Venous and Arterial Blood After Oral Ingestion, 26 (5) Eur. J. Clin. Pharmacol., 619 (1984). As referenced at http://www.nacdl.org/public.nsf/UNID/9EB0EB2E6BACCE3885257077004B5C88?OpenDocument


One of the most well known blood experts in the country identifies the following problems with determining alcohol concentrations in breath:

"Phase of ethanol metabolism

Arterio-venous differences

Source of blood analyzed; arterial, venous, capillary

Blood hematology; hematocrit value, salt, fat, and protein content

Intra-pulmonary gas pressure

Ambient temperature and humidity

Expired-breath temperature

Breathing pattern; hypo-and hyper-ventilation

Bronchopulmonary disease

Presence of mouth alcohol

Regurgitation of stomach fluids

Phase of exhalation; end expiratory or top-lung air

Breath specimen; rebreathed, end-expired, mixed expired

Body temperature; hyperthermia-hypothermia[1]

Many of these defenses require an expert witness

[1] A. W. Jones, Physiological Aspects of Breath Alcohol Measurement, Alcohol, Drugs and Driving, Volume 6 Number 2, Pg. 15 (1990). Hereby referenced as Jones.

Disclaimer: Past results do not guarantee a future outcome. Results include cases in both Massachusetts and New Hampshire. Attorney Dan Hynes is admitted to practice law only in Massachusetts and New Hampshire. This website may be considered advertising. Contacting us does not create an attorney/client relationship and the information on this site is not legal advice and may be inaccurate or not applicable to your case. Each case is different.

Mailing Address: Dan Hynes PO BOX 598 Merrimack, NH 03054