Smart & Aggressive
attorneys defending you.
click for a free consultation

Ignition Interlock: How Arizona Law Applies to Breath Test Machines

Arizona was one of the first states to implement a mandatory ignition interlock device installation with a person’s first Driving Under the Influence (DUI) offense. At the time, only two other states in the nation had such strict laws and, currently, only fifteen other states require installation with a first offense when the driver has a blood alcohol content (BAC) reading of 0.08 or more.

An ignition interlock device, also known as a breath test machine, is used to prevent drivers from operating a vehicle after consuming alcohol. Although the law was recently changed from an installation requirement of one year to a potential six month deferment after six months, the use of a breath machine with someone’s first DUI conviction remains one of the harshest in the nation.

In addition to being required to install the device, those who receive the penalty are also required to cover installation and monthly maintenance costs. Installation is estimated to run $120 while an additional maintenance fee can average $80 per month. These costs can add up quickly and knowing both how the device works and how Arizona state law applies can give you the tools necessary to ensure that the device is not on your vehicle any longer than it needs to be.

How a Breath Test Machine Works

The ignition interlock device is a bit larger than a cellphone and is wired directly into a vehicle’s ignition system. It is installed on the dashboard and requires the driver to exhale a breath sample into the device before the engine will start.

In addition to the initial sample, the device may require additional random samples throughout the time the car engine is running. These are referred to as “rolling tests.” If the driver does not provide a breath when requested, a warning will sound and an alarm will be triggered until the ignition is turned off.

These rolling tests are designed to reduce the risk of drivers using friends to provide breath samples and to keep the driver from consuming alcohol after the ignition has been started. It is important to note that, as a safety measure, the machine will not turn off an already running engine.

The machine uses a breath sample because, if alcohol is present in the driver’s body, it will be present within the breath sample. Ultimately, blood reaches the lungs where it exchanges carbon dioxide gathered throughout the body for oxygen. If alcohol is present, it is also released within the lungs and travels out with the breath sample. As a result, a blood alcohol content level can be estimated based on the alcohol found within one’s breath.

If a breath test machine provides a reading that is over a pre-set level, the car will not start. The reading is also noted on the system’s computer chip and a recorded report can be downloaded and provided to law enforcement officers or used as evidence in court. The reports also record if the machine has been tampered with.

The flaws in this system are obvious. Many times, the machine inaccurately reads other substances (like fructose) as ethanol or drinking alcohol. Being aware of this can help avoid the imposition of additional interlock time unnecessarily.

Arizona Laws and Breath Test Machines

Arizona state law requires that a breath test machine be installed by a company authorized by a local motor vehicle department. Once installed, the device requires calibration and inspection by a certified installer every 30 days for the first three months. After this period, the certified installer will designate an inspection and calibration schedule. During these inspections, data logs are downloaded and the device inspected to see if there is any evidence of tampering.

Failure to comply with Arizona law may carry serious consequences. If a driver fails to use an ignition interlock device as required, use of the machine may be extended for an additional six months to a year. In some cases, driving privileges can be suspended indefinitely.

Navigating through the strict breath machine laws in Arizona can be frustrating and difficult. As a result, if you have been arrested for DUI, it is wise to seek the counsel of an experienced DUI defense lawyer to better ensure your legal rights are protected.

Contact Us


  • All fields required *
  • This field is for validation purposes and should be left unchanged.
  • This field is for validation purposes and should be left unchanged.