There are two parts to DUI investigation, chemical testing and field testing/observations.

Chemical Testing

Connecticut law provides for three different methods for testing a person’s blood for the presence of alcohol or drugs. These tests may show that they operate under the influence. Each methods has its strengths and weaknesses. Depending on your case, you may take one or more of the following tests. So, you should hire an educated DUI defense attorney who knows the defenses to each of the methods of testing. Attorneys Jim Ruane and Jay Ruane have advanced training in the defense of chemical testing. Attorney Jay Ruane is a certified breath testing technician by the US Department of Transportation.

Blood Testing

Blood testing is the least common type of testing for routine DUI cases. But, it is the most common type of testing following accidents. This testing at hospitals uses many different methods, with enzymatic immunoassay and gas chromatography being the two most common.

An immunoassay is a biochemical test that measures the concentration of a substance in a biological liquid. It usually measures serum or urine using the reaction of an antibody or antibodies to its antigen. The assay takes advantage of the specific binding of an antibody to its antigen.


Gas-liquid chromatography (GLC), or simply gas chromatography (GC), is a common type of chromatography. It gets used in analytic chemistry for separating and analyzing compounds that can vaporize without decomposition. In gas chromatography, the moving phase (or “mobile phase”) is a carrier gas. This usually consists of an inert gas such as helium or an unreactive gas such as nitrogen. The stationary phase is a microscopic layer of liquid or polymer on an inert solid support. It exists inside a piece of glass or metal tubing called a column. This relates to the fractionating column used in distillation.

The instrument used to perform gas chromatography is called a gas chromatograph (or “aerograph”, “gas separator”). The gaseous compounds analyzed interact with the walls of the column. Different stationary phases coat the walls of the column. This causes each compound to elute at a different time, known as the retention time of the compound. The comparison of retention times gives GC its analytical usefulness.

Blood alcohol tests have the following characteristics:

  • Blood alcohol testing is one of the most accurate methods for testing a person’s blood alcohol content (BAC).
  • BAC tests are one of the most expensive methods for testing a person’s blood alcohol content.
  • BAC testing is the most intrusive method currently in use for testing blood alcohol content because it requires the drawing of blood from the body by a needle.
  • Blood alcohol tests are typically the least common method when testing for alcohol. This results from heir high cost and their intrusiveness.

 Breath Testing

Blood alcohol levels used to define impairment from alcohol poisoning. Some observed that most people showed measurable mental impairment at around 0.05% blood alcohol concentration (BAC). Above this level, motor functions deteriorate progressively with increased blood alcohol concentrations. For the average person, unconsciousness results by 0.4% BAC. Above 0.5% BAC, basic body functions such as the breathing or the beating action of the heart can depress to the point of death. 

Blood originally measured alcohol concentrations in the human body. Blood tests offer the ability to accurately test the same sample several times, if the sample gets maintained properly. One disadvantage with blood analysis is that the collection process requires trained medical personnel. Also, the sample collection is invasive and the analysis requires precise procedures by trained lab technicians. Finally, the results are not immediately available and the overall process is costly.

In the 1930s the pioneers in the development of breath alcohol testing took advantage of the fact that alcohol exists in the deep lung breath in proportion the alcohol found in the blood. Breath testing instruments capture a sample of alveolar breath for analyses. Some of the early instruments were crude. But today, breath analytical instruments have evolved into low cost, highly accurate, rapid analytical system. They simply and painlessly collect a sample and calculate a result. Although a trained operator needs to do this, the collection and analysis process is simple. Connecticut has authorized the use of infrared breath testing for alcohol.

Intoxylizer 500

Currently, police departments use the Intoxilyzer 500 machine. But, they are in the process of transitioning to a new machine from the Draeger corporation. Breath testing by infrared analysis all works on the same concept, now matter what company makes the machine. All molecules are constantly vibrating, and these vibrations change when the molecules absorb infrared light. The changes in vibration include the bending and stretching of various bonds. Each type of bond within a molecule absorbs infrared light at different wavelengths. Therefore, in order to identify ethanol in a sample, one must look at the wavelengths of the bonds in ethanol (C-O, O-H, C-C) and measure the absorption of infrared light. The absorption wavelengths help to identify the substance as ethanol. Also, the amount of infrared absorption tells you how much ethanol is present.

Breath Machine Cells

All breath machines have a cell into which a person blows their lung air. There is an inlet for the cell and there’s an exhaust portion of the cell, and a sample chamber that the breath travels through. The light source is like a regular light bulb, producing energy. It is the same type of energy that an electric stove emits and that one can feel when the burner turns red. The sensor converts the light to an electrical pulse. The computer system does not automatically recognize that type of signal. It has to get converted to a digital signal and then sent to the computer. Here, it gets reduced to numerical values. That numerical value shows on a small screen on the face of the device. It prints a readable report or readable result.

Breath testing has its basis in the principle known as Henry’s Law. This relates to blood in a closed container that contains alcohol. The alcohol will evaporate until the concentration in the air above the liquid is equal to that in the liquid, also known as a fixed constant or Henry’s Constant. The ratio given to that of the blood in the human body used in accordance with Henry’s Law is 2100:1. This can be explained as “the concentration of alcohol in a normal person’s blood is said to be approximately 2100 times as great as the concentration in the air in equilibrium with it. This means that if the alcohol concentration found in blood that is in equilibrium with the alcohol in air, the alcohol concentration in the blood should be close to 2100 times greater.”

Other Issues

Another problem exists by this normal ratio because not every person has the same body weight, frame and physical makeup, therefore there cannot be a norm for their blood/air equilibrium. The ratio can widen depending on the person tested because the human body does not work as an ideal subject for a sealed container. Because of this problem with the normal ratio determined by forensic scientists, there exists up to a 0.03% error or more with a breath machine.

In addition to the issues of the ratio of the breath machine, the temperature of the individual supplying the sample can impact the reported results. Rarely does a person take the defendant’s temperature when they take the test, but it could severely alter the results of the test! A temperature increase of only 2°F will cause approximately a 10% increase in BAC due to the volatility of alcohol. A drop in temperature can cause similar results. A heavy dose of aspirin can cause body temperature to reduce and thus potentially alter results. These two issues of breath can be used as a viable defense when being charged with a DUI. If you have taken any medication or have been sick, it is a good idea to tell the officer when they question you, or to tell your attorney afterwards.

Also, if you have any medical conditions that could affect your normal blood ratio, you should let your attorney know so that they may obtain the correct medical documentation to support your claims. If you are a diabetic, the officer and your attorney should know because a diabetic can naturally produce ketones, which can skew the results of the breath test. A dedicated DUI attorney can review your medical history and investigate any possible medical defenses to the charges brought against you.

Urine Testing

Police officers turn to urine tests to measure your intoxication levels of drugs or alcohol consumption if a breath or blood test is unavailable. Many times urine tests happen when the breath tests comes back below the legal limit. Urine tests don’t pinpoint the time of consumption, an important part of the state’s prosecution of a DWI case, as the state of Connecticut must prove your BAC exceeded 0.08 at the time of driving, not the time of the testing.

In Connecticut, if you took a urine tests, the results get mailed to you after the state laboratory processes the results. This may be after your first court date, so it is important to contact a Ruane Attorney as soon as possible to see what other records we need to defend your case. Urine tests most often happen when the police suspect drugged driving.

Test Administration

These tests are a very ineffective method of testing because they do not show a level of impairment, only a level of presence of drugs in a system. For example, marijuana may stay in a person’s system for up to five weeks and if you use chronically, your urinalysis will say you were on marijuana at the time of driving, when it could have been days since you last smoked. In addition, urine tests must get handled in much the same way as blood samples.

The person administering the test must be a professional, the sample must be taken in a sanitary place, and the sample’s journey to the laboratory must be documented completely. If the state’s documentation neglects to mention any part of the trip taken by the sample on its way to the lab, the evidence could get thrown out of court. Unless your attorney challenges this, you waive those defenses. Our lawyers have training to fight the admission or urine test evidence on every possible front.

  • They have a high assurance of reliable results.
  • They are relatively inexpensive.
  • These tests provide the most flexibility in testing different drugs, including alcohol and nicotine.
  • They are the most likely of all drug-testing methods to withstand legal challenge.

Urine Alcohol Testing Cons

  • The specimen can get adulterated, substituted, or diluted.
  • They have a limited window of detection (typically one to five days).
  • They constitute an invasive or embarrassing form of alcohol testing.
  • These tests present a biological hazard when the specimens get handled and shipped to the lab.
  • They indicate the presence of alcohol in a person’s system, but it takes up to two hours for the alcohol to show up in urine. A positive urine test does not necessarily mean the person was under the influence of alcohol at the time of the test.

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