New Jersey DWI: Understanding the Alcotest 7110’s Operation

Unlike Pennsylvania, New Jersey doesn’t use a breathalyzer to determine a person’s blood alcohol content (BAC) after a DWI arrest.  While New Jersey does still have two authorized breathalyzer models, the majority of counties use the Alcotest 7110 which is otherwise known as the Draeger Alcotest 7110. This is the most used breath testing device because the Garden State believes it to be the most reliable way to determine a person’s BAC.

The Alcotest uses two different technologies which operate at the same time to measure the alcohol concentration in a breath sample. When a person provides a breath sample the molecules of ethanol are tested by each of these technologies. These technologies are infrared (IR) and electro-chemical (EC) energy. When a person provides a breath sample, it passes through a small chamber in the device known as a Cuvette and a beam of infrared energy passes through the molecules of the sample. The Infrared energy will measure the difference in the energy between what was initially emitted from the devices and what was ultimately detected. This is the IR testing technology. The Alcotest will also test the sample using the electro-chemical technology.

The machine will then compare the two samples and provided that the results are within an acceptable range of each other the test will deemed to be accurate by the machine’s software and therefore valid. The Alcotest is preferred over the Breathalyzer because of a procedure known as “bracketing.” With a Breathalyzer device the machine is inspected once every sixty days with one inspection being done before the Defendant provides a sample and one inspection being performed after the sample. The two inspections, therefore, are essentially “bracketed.” The inference is that if the Breathalyzer is working before and after the Defendant provides a sample it was probably working at the time of the sample. With the Alcotest, however, the “bracketing” is done immediately with control tests using a predetermined alcoholic solution before and after each sample.

The Alcotest is mostly dependent on the reliability of the machine’s software and the operability of the hardware whereas the Breathalyzer is more dependent on the operator’s compliance with testing procedures. The Alcotest will not permit the operator to even proceed with the test if the proper procedures aren’t followed. There is really nothing, however, stopping an operator of a Breathalyzer from using that device improperly. This is the reason why in New Jersey a proper DWI defense is not only focused on the operability and the reliability of the Alcotest’s software but also issues like 20 minute observation period and other pre-testing procedures which the machine can’t control. In addition, these issues a good criminal defense attorney in New Jersey, Pennsylvania or any other jurisdiction wants to focus on what happened before the arrest, specifically the field sobriety tests.  The field sobriety test are standard regardless of the jurisdiction.  These tests as well as issues such as probable cause are all discussed in my DUI book.  If you have questions about DWI in New Jersey or DUI in Pennsylvania, I encourage you to call my office today.

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