Interlock Device vs Car Breathalyzer

August 8, 2019

In recent years, ignition interlock devices have been at the forefront of the battle to reduce drunk driving recidivism. Now, almost every state in the nation has some variation of laws about IIDs for alcohol-related driving offenses. So, if you have a DUI conviction, you’ll likely be court ordered to have a car breathalyzer (IID) installed in your vehicle. 

With all the requirements and terms, it can quickly become confusing, especially because there are quite a few names for these drunk driving prevention devices. For example, you might wonder whether there’s a difference between a car breathalyzer and interlock device? Below, we’ll answer that question and many others you might have. Read on to find out. 

Interlock Device vs Car Breathalyzer

These days, breathalyzers have become a part of the modern vocabulary and is often used to generally describe any device that tests blood alcohol concentration via a breath sample. It can be broadly applied to both the device police use in field tests or the device that prevents motorists from operating a vehicle under the influence; however, when you hear the phrase “interlock device,” or “car breathalyzer,” they’re referring to the same thing. 

Common names for an IID include:

  • Alcohol ignition interlock 
  • Breath alcohol ignition interlock device
  • Car breathalyzer
  • Ignition interlock device
  • IID
  • In-car breathalyzer
  • Ignition interlock
  • Interlock
  • Interlock device

What is an Ignition Interlock Device?

As we’ll delve into later, ignition interlock devices have been around in one form or another for since 1969. As time and technology progressed, updates were made to the device to improve its functionality, accuracy, ease of use, and reliability. At their essence, an IID is simply the incorporation of two different devices:   

  • A breathalyzer – A device that takes a sample of a person’s alveoli breath and then gauges a person’s blood alcohol concentration (BAC).  
  • An immobilizer – An electronic safety mechanism that is hooked up to the vehicle’s ignition system and engine and prevents the engine from turning on unless a signal is received.  

The happy union of these two separate machines has been an incredibly effective measure for reducing drunk driving, especially recidivistic drunk driving. According to the CDC:

In 2012, an estimated 4.2 million U.S. adults reported driving while impaired by alcohol at least once in the preceding 30 days, resulting in an estimated 121 million alcohol-impaired driving episodes annually, and a national rate of 505 episodes per 1,000 population.

What’s truly terrifying about this statistic is that, on average, a driver will operate their vehicle in an intoxicated state approximately 80 separate times before ever getting pulled over for a DUI charge. In addition, a NHTSA study found that one in four drunk drivers who have already been convicted with a DUI will become a repeat offender within five years. These staggering figures highlight why there’s been such a concerted effort to have interlock devices be a standard punishment, even for a first-time DUI offender. As the study states:

A number of interventions have been implemented over the past 20 years that are designed to reduce recidivism among DWI offenders. Some of these interventions are applied judicially; others through administrative action. They include DWI courts, alcohol ignition interlocks, vehicle and license plate sanctions, and various forms of close supervision of DWI offenders. Evaluations for many of these interventions can be found in Countermeasures That Work and published elsewhere in the literature (NHTSA, 2010). Some or all of these interventions may have played a role in the reduction of DWI recidivism over the past 20 years.

Interlock Device Requirements

If you’ve been mandated by law to install an IID in your vehicle, you may be curious about what that entails and what’s required of you. To begin, you’ll have to take the following actions:

  • Get an Ignition Interlock Limited License (IILL) – Depending on your state, you may need to apply for an IILL. This grants a restricted license to individuals whose driving privileges have been suspended or revoked as a result of a DUI. This permits a motorist to drive a vehicle, so long as they have an ignition interlock device installed. 
  • Rent an IID – You must lease your device from a state-licensed interlock provider such as Low Cost Interlock (LCI). The device must be installed by a state-certified technician and you’ll have to pay for all the fees associated with the rental and installation of the device. 
  • Recalibrate the device – Calibration is specific to each case and may be required every 30, 60, 90 or 180 days. This is dependent on the individual client and the jurisdiction they are utilizing the IID in. 

During this time, an LCI technician will do the following:

  • Test the device for accuracy and adjust accordingly
  • Download the data log 
  • Analyze the data log for warnings and/or violations. If any are found, the state DMV will be immediately notified

Using an Ignition Interlock Device 

You may be curious how the interlock device actually works. The device itself is rather simple. It’s composed of two key components: 

  • Relay Module – The part that analyzes the breath sample and decides whether or not it falls below the limits. If the sample does indeed pass, the device will send a signal to the immobilizer, granting it permission to turn on the engine.  

With this in mind, there are two different times you’ll be required to provide a breath sample. 

Starting the vehicle – You’ll have to give an initial breath sample to start the car. Upon providing a breath sample, the device will analyze the air and then decide whether or not you are fit to drive. If it detects alcohol on your breath, the car won’t turn on and you’ll receive a warning. After a few minutes, you’ll be able to provide another breath sample. Multiple failed attempts will be noted, logged as a violation, and result in a complete lockout, which would require your service provider to reset. 

  • Extension of the interlock device
  • Suspension of limited license 
  • Additional fees or fines
  • Possible jail time

If the device notes that you’ve attempted to start the vehicle with a blood alcohol content of .08 or higher, it will automatically log the test as a violation. Violations can result in any of the following punishments:

Rolling Retests – Every IID is required by law to perform an additional breath test known as a rolling retest within minutes of the initial breath sample. This countermeasure is intended to prevent drivers from cheating the device by having a sober person give the breath sample. 

While driving, the device will alert the motorist that it’s time for a rolling retest. The driver will then have approximately 7 minutes to provide a passing breath sample. If the sample is a failure or if the driver refuses to give a sample, the device will automatically note the failure as a violation and then cause the car’s horn and lights to continuously honk and flash. This response is meant to warn others on the road, including police, that the driver is operating the vehicle under the influence. But, it should be noted that the car won’t ever automatically shut off, since this would endanger both the driver and other motorists. 

The History of Ignition Interlock Devices

There have been several key occurrences in the evolution of the modern car breathalyzer. That road to progress has been impacted by many inventors, the most important of which include:

  • St. George Evans and Edward Birkenbuel – In 1919, George Evans and Edward Birkeenbuel invented the electric immobilizer/alarm system. This system utilized a manual switch that would kill the engine and sound the vehicle’s horn if a person attempted to turn on the vehicle. 
  • Emil Bogen – In 1927 Doctor Emil Bogen published a paper entitled, “The Diagnosis of Drunkenness—a Qualitative Study of Acute Alcohol Intoxication.” In it, he made the discovery that measuring blood alcohol concentration wasn’t simply limited to blood tests and that it could be reliably analyzed by testing alveoli air.
  • Rolla Neil Harger – In 1936, Doctor Rolla N. Harger, a professor emeritus of biochemistry and toxicology at Indian University, used Bogen’s work to create the Drunkometer. This crude device was the first-ever apparatus capable of measuring alcohol in a breath sample. How it worked was relatively simple, a person blew into a balloon, which was then taken to a laboratory for analysis. The sample was passed through a chemical solution which would change colors if alcohol was detected. 
  • Robert Borkenstein – In 1956, Robert Borkenstein, created a device that removed the need for a lab test. He named it the Breathalyzer and it became the first field test unit capable of measuring a breath sample right then and there by using photometry and chemical oxidation. For the next decade, Borkenstein’s breathalyzer became the primary BAC field testing device nationwide. 
  • Bill Dulcie and Tom Jones – In 1967, Englishmen Bill Dulcie and Tom Jones created the first electronic breathalyzer. This faster and more accurate unit eventually phased out Borkenstein’s device. 
  • Borg Warner Corporation – In 1969, the first prototype of the ignition interlock device was created by the Bork-Warner Corporation of Des Plaines, Illinois. This research laboratory took Dulcie and Jones’ electronic breathalyzer and combined it with Evans and Birkenbuel’s immobiliser. The concept was eventually realized thanks to the schematic conception by Jeffrey Feit in 1981, and it’s working version by Hans Doren in 1983.  

Over the years, car breathalyzers have been updated according to the technology of the times, getting better, faster, and more accurate with every passing year. Today, car breathalyzers are incredibly precise and make the original BAC testing methods look like relics of the past. 

How Do I Get Started?

Are you curious as to how you’d go about getting an interlock device installed? If so, you shouldn’t worry. With Low Cost Interlock, the process is simple and the pricing transparent. 

To get the ball rolling you’ll first need to fill out an application with LCI. Ignition interlock cost will differ on a state-by-state basis, so providing LCI with all your information is necessary for an accurate pricing estimate. The information needed will include the following: 

  • First and last name
  • Home address
  • State
  • Zip Code
  • Contact information
  • Driver’s license number 
  • Vehicle registration information including VIN and license plate 
  • Court papers and/or DMV papers which state:
    • Case number
    • Court address
    • Presiding judge
    • Your attorney
    • County

Upon providing this information, LCI will give you a comprehensive appraisal. This ensures that you won’t be surprised by any hidden fees, and that you will know exactly what you’re signing up for. To provide even better service, LCI doesn’t charge you for shipping, set-up, or installation. If you join today, you’ll also save an additional $100 off your pricing. 

The LCI car breathalyzer is:

  • Simple and easy to use – No complicated breathing patterns, simply exhale for 3 seconds. We want you to blow and go with no hassle involved. 
  • Accurate – LCI guarantees 100% accuracy in breath sample readings. 
  • Discreet – If you want the most discreet breathalyzer on the market, the LCI Can was created for you. This IID looks like a soda can, so when you provide a breath sample everyone will assume you’re just having a drink. 
  • Convenient – LCI services various locations in more than 25 states, ensuring that both installation and recalibration is convenient for you. 
  • Customer Service – LCI provides around the clock bilingual customer support. If you have any issues or questions, rest assured that there’s a service operator ready and able to help you troubleshoot or problem solve. 
  • Sanitation – The LCI device is the most sanitary on the market. After its done being used, every breathalyzer is sent back to headquarters and thoroughly cleaned and then tested for sanitation. 

Your Interlock Device 

IIDs have worked wonders in making the roads a safer place. Frankly, it doesn’t really matter whether you call them car breathalyzers or ignition interlock devices, since they’re synonymous terms. With this in mind, if you need to have an IID installed in your vehicle, reach out today and LCI can help get you back on the road as quickly as possible. 


CDC. Alcohol-Impaired Driving Among Adults. (2015).

NHTSA. Traffic Safety Facts. DWI Recidivism in the United States. (2014).

Wikipedia. Immobiliser.

Bogen, E. NCBI. The Diagnosis of Drunkenness—a Qualitative Study of Acute Alcohol Intoxication. (1927).

NYT. Rolla N. Harger Dies; Invented Drunkometer. (1983).

Woo, E. LAT. Robert Borkentstein, 89; Inventor of Breathalyzer Intoxication Tester. (2002).

Edubilla. Breathlyzer – Invented by Robert Borkenstein.

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