Ignition Interlock Device vs Breathalyzer: Key Differences and Applications

In your quest to understand the differences between ignition interlock devices and breathalyzers, you may have encountered various opinions and information sources. Both systems aim to promote safe driving and prevent alcohol-impaired driving, but they differ in their operation, application, and purpose.

Ignition interlock devices are installed in vehicles and require a breath sample before you can start your car. If your blood alcohol concentration (BAC) is above a predefined limit, the device will prevent the vehicle from starting. On the other hand, a breathalyzer is a portable device used by law enforcement or individuals to measure their BAC before getting behind the wheel, providing a self-assessment rather than physically restricting their ability to start the car.

As you continue reading, you will explore how each device functions, their pros and cons, and which is more suitable in various situations. This information can help you make informed decisions about promoting safe driving habits and complying with legal requirements.

Overview of Ignition Interlock Device and Breathalyzer

What Is an Ignition Interlock Device?

An ignition interlock device (IID) is a small, car-mounted breathalyzer that prevents your vehicle from starting if your blood alcohol concentration (BAC) is above a predefined limit1. Typically, the IID is installed in your vehicle’s ignition system and requires you to provide a breath sample before starting the engine. If the breath sample indicates a BAC above the set limit, the vehicle will not start. IIDs have been proven effective in curbing drinking and driving when installed in vehicles2.

What Is a Breathalyzer?

A breathalyzer, on the other hand, is a portable device designed to measure your BAC by analyzing the alcohol content in your breath. Breathalyzers are commonly used by law enforcement officers during roadside stops to determine if a driver is impaired. These devices provide a quick and non-invasive method for estimating a person’s BAC, however, they are not integrated into your vehicle like IIDs.

Feature Ignition Interlock Device Breathalyzer
Purpose Prevents vehicle from starting if BAC is above the limit Estimates BAC for roadside testing or personal use
Integration Installed in the vehicle’s ignition system Handheld, portable device
Usage Required before starting the vehicle On-demand, discreet use
Deterrent Directly prevents intoxicated driving Provides BAC level for informed decision-making

Avoid making exaggerated or false claims. Add a comparison table at the end of the section. Use a professional tone of voice. You must write in the following point of view: Second Person (you, your, yours, etc)


  1. https://www.sciencedirect.com/science/article/pii/S0749379710007105

  2. https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD004168.pub2/abstract

Functionality and Purpose

How Ignition Interlock Devices Work

Ignition interlock devices (IIDs) are designed to prevent drivers from starting their vehicles if their blood alcohol content (BAC) is above a predefined limit. To use an IID, you need to blow into the device’s mouthpiece, which analyzes your breath for alcohol content. If your BAC is below the limit, the vehicle’s ignition system is unlocked, and you can start the car1. While driving, the IID may prompt you for random retests to ensure continuous sobriety.

How Breathalyzers Work

A breathalyzer is a portable device that helps estimate your BAC by measuring the alcohol level in your breath. When you blow into the breathalyzer’s mouthpiece, it converts the alcohol content in your breath into an electrical signal, which is then displayed as a numeric value2. Breathalyzers are commonly used by law enforcement as a field sobriety test to determine if a driver is under the influence of alcohol.

Preventing Drunk Driving

Combining the functionality of IIDs and breathalyzers plays a crucial role in preventing drunk driving3. IIDs serve as an effective deterrent, as they physically prevent a driver from starting a vehicle if their BAC is above the limit. This makes it harder for intoxicated individuals to get behind the wheel, reducing the risk of alcohol-related accidents.

On the other hand, breathalyzers are primarily used for detection and enforcement, helping identify intoxicated drivers on the road. Their portability and ease-of-use allow law enforcement officers to perform on-the-spot tests, making roads safer for everyone.


  1. http://utpedia.utp.edu.my/id/eprint/15985/


  3. https://www.sciencedirect.com/science/article/pii/S0749379710007105

Installation and Use

Installing an Ignition Interlock Device

To install an ignition interlock device, you will first need to choose a state-approved provider to correctly install the device in your vehicle. The installation process typically takes between 1 to 3 hours, depending on the type of vehicle you have. During installation, the ignition interlock device is connected to your vehicle’s ignition system, which will prevent the vehicle from starting if alcohol is detected on your breath.

After installation, it’s essential to maintain the device properly and follow any state-specific requirements or guidelines regarding regular calibration and service appointments. Many states mandate periodic service visits to ensure that the device is functioning correctly and to download the logged data for monitoring purposes. Failure to comply with these requirements may result in penalties or even removal from the ignition interlock program.

Using a Breathalyzer

Using a breathalyzer is relatively simple and straightforward. First, turn on the device and wait for it to warm up and display a ready signal on the screen (some devices may require a specific warm-up period). Then, take a deep breath and blow steadily into the mouthpiece until you hear a beep or feel a slight click, indicating that the test is complete.

Within seconds, the breathalyzer will display your blood alcohol content (BAC) reading on the screen. It is crucial to wait at least 15 minutes after eating, drinking, or using mouthwash before performing a breath test to ensure accurate results.

If you use a personal breathalyzer, remember to replace the mouthpiece as recommended by the manufacturer and calibrate the device regularly (typically every 6-12 months) to maintain accurate readings.

By carefully installing and using an ignition interlock device or a breathalyzer, you can take proactive steps to avoid driving under the influence and ensure the safety of both yourself and others on the road.

Legal Implications

Ignition Interlock Device Laws

Ignition interlock devices (IIDs) are designed to prevent alcohol-impaired driving by requiring a breath test before starting a vehicle. Many states in the US have enacted laws requiring IIDs for certain DUI offenders. Specifically, these devices are mandated for individuals convicted of DUIs or with multiple alcohol-related offenses 1. Additionally, some states require the installation of IIDs for first-time offenders with a high blood alcohol concentration (BAC), typically at 0.15% or higher 2. You should check your state’s laws to determine the requirements for IID installations and usage.

It’s worth noting that some countries, such as France, have implemented laws making portable breathalyzers mandatory in all vehicles 3. This indicates a growing global trend towards using technology to combat drunk driving.

Breathalyzer Laws and Regulations

Breathalyzer tests are commonly used by law enforcement officers to determine an individual’s BAC during a traffic stop or DUI investigation. Various laws and regulations govern the use of breathalyzer tests, as well as the consequences of failing or refusing to take one.

In the US, all states have “implied consent” laws, which mean that by obtaining a driver’s license and operating a vehicle, you implicitly agree to submit to a breathalyzer test if requested by a law enforcement officer. Refusing to take the test can result in penalties such as license suspension and fines, regardless of whether you were actually intoxicated or not4.

You should also be aware that legal BAC limits vary depending on age and the type of vehicle being operated. For example, the legal limit for drivers aged 21 and over is generally 0.08% 5, while for commercial drivers, the limit is typically lower at 0.04%6. Drivers under the age of 21 are subject to stricter “zero-tolerance” laws, with BAC limits often set at 0.01%-0.02%7.

To ensure the accuracy of breathalyzer test results, devices must be properly maintained and calibrated. Moreover, law enforcement officers must be trained in using these devices and administering tests in accordance with standardized procedures8. Failure to adhere to these requirements could potentially lead to inaccurate test results and potential legal challenges.


  1. https://www.cambridge.org/core/journals/journal-of-law-medicine-and-ethics/article/us-state-ignition-interlock-laws-for-alcohol-impaired-driving-prevention-a-50-state-survey-and-analysis/ABABC109EBDB1332CD19C241002E0676

  2. https://www.nhtsa.gov/risky-driving/drunk-driving

  3. https://www.tandfonline.com/doi/abs/10.1080/15389588.2013.825042

  4. https://dui.drivinglaws.org/resources/dui-refusal-blood-breath-urine-test.html

  5. https://www.nhtsa.gov/risky-driving/drunk-driving

  6. https://www.fmcsa.dot.gov/regulations/title49/section/382.201

  7. https://www.iihs.org/topics/alcohol-and-drugs/dui-laws/video-tag/2019#zero-tolerance-laws

  8. https://dui.findlaw.com/dui-charges/Breathalyzer-calibration-.html

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