What Breathalyzer Do Police Use? Roadside vs Station Devices, the Brands Behind Them and What It Means for Your Own Tester

Updated 30 Oct 2026 · Written by Daniel Brooks · Medically reviewed by Dr. Maya Chen, PharmD

Police in the US use two different kinds of breathalyzer, brother, and most people don't realize it. There's the small handheld unit an officer might hand you at the roadside, called a preliminary breath tester, and there's the bigger evidential instrument, usually at the station, that produces the number used in court. They use different technology, they're held to different standards, and they're made by a short list of companies. Knowing how they work also helps if you're shopping for your own breathalyzer, because the best personal units use the same type of sensor as many police handhelds. Here's the rundown.

This is general information, not legal advice. DUI laws and police procedures vary by state, so check your state's rules if you're dealing with a real case, and talk to a lawyer. A personal breathalyzer is for your own awareness only. It doesn't make it safe to drive, and the only safe amount to drink before driving is none.

The short version

• Roadside: officers often use a handheld preliminary breath tester (PBT), usually with a fuel-cell sensor. It helps them decide whether to arrest.
• At the station: the number used as evidence usually comes from an evidential breath test (EBT) instrument, typically using infrared, sometimes plus a fuel cell.
• Common makers include Intoximeters, Lifeloc, Dräger, CMI (Intoxilyzer) and National Patent Analytical Systems (DataMaster).
• Devices are chosen from NHTSA's Conforming Products Lists, and states approve specific models.
• Evidential tests come with rules: a waiting and observation period, usually two samples that must agree, and regular calibration checks.
• For personal use, a fuel-cell breathalyzer is the closest thing to a police handheld.

Two jobs, two kinds of device

It helps to think of police breath testing as two separate steps.

Step one is screening. At a traffic stop, if an officer suspects drinking, they may ask you to blow into a handheld PBT. This is a quick check. The result helps the officer decide whether there's enough reason to arrest. In many states, PBT readings aren't used as the main evidence of your BAC in court, though rules differ.

Step two is evidence. After an arrest, you'll usually be asked to give breath samples on an evidential instrument, often a desktop unit at the station or in a mobile testing vehicle. This is the reading that typically goes in the report and gets used in court. These instruments are built and maintained to a stricter standard.

Some states also use blood tests instead of, or as well as, breath tests, for example when a driver can't give a breath sample or drugs are suspected.

Roadside units: preliminary breath testers

PBTs are small, battery-powered and built to survive life in a patrol car. Most use a fuel-cell sensor: alcohol in your breath reacts at a platinum electrode and makes a tiny electrical current, and the more alcohol, the more current. Fuel cells are specific to alcohol and much less likely than cheap sensors to be fooled by other substances.

Models you'll commonly see named in police use include:

• Intoximeters Alco-Sensor FST and other Alco-Sensor models
• Lifeloc FC10 and related Lifeloc units
• Dräger Alcotest 6000-series handhelds, such as the 6820

Departments pick models that are on NHTSA's list of approved screening devices and approved by their state. The exact model varies from agency to agency.

Many PBTs also have a "passive" mode that can detect alcohol in the air near someone's mouth without a full blow, as a quick screen. The officer then asks for a proper sample if needed.

Station units: evidential breath instruments

Evidential instruments are larger, more expensive and more controlled. Most use infrared spectroscopy: a beam of infrared light passes through a chamber holding your breath sample, and ethanol absorbs certain wavelengths. The amount absorbed tells the machine how much alcohol is there. Some instruments use both infrared and a fuel cell as a cross-check.

Instruments that state programs have commonly used include:

• Intoxilyzer 8000 and 9000, made by CMI
• DataMaster DMT, made by National Patent Analytical Systems
• Dräger Alcotest 9510
• Intoximeters EC/IR II and similar Intoximeters instruments

Each state chooses its own approved instruments, often through a state toxicology lab or health department, from devices on NHTSA's Conforming Products List for evidential breath measurement devices. Some states use one model statewide; others approve several.

Why evidential tests follow strict rules

Because the evidential number can decide a case, the process around it matters as much as the machine. Common features include:

• A waiting and observation period. Often around 15 to 20 minutes, depending on the state. The officer watches you to make sure you don't eat, drink, smoke, vomit or burp. The point is to let any alcohol left in your mouth clear, because mouth alcohol can push a reading up.
• Air blanks. The machine checks the room air and its own chamber are clear before each sample.
• Two samples. Many states require two breath samples taken a few minutes apart that agree within a set tolerance. If they don't, the test may be repeated or treated differently.
• Calibration and accuracy checks. Instruments are regularly checked against a known alcohol standard, either a wet-bath simulator or a dry-gas canister, and these checks are logged.
• Trained operators. Officers running evidential tests are typically certified on the specific instrument.
• Records. Maintenance logs, calibration records and test printouts are kept and can be requested in a case.

Our page on how a breathalyzer works explains the science behind these steps, including the 2100:1 breath-to-blood ratio that turns a breath reading into a BAC figure.

Roadside vs station: side by side

What about refusing?

We won't give legal advice here, but you should know the basics exist. Every state has "implied consent" rules, meaning that by driving you've agreed to chemical testing under certain conditions, and refusing an evidential test after arrest usually carries penalties such as a licence suspension, separate from any DUI charge. Rules on refusing the roadside PBT differ by state. The US Supreme Court held in Birchfield v. North Dakota (2016) that police can require a breath test without a warrant after a lawful drunk-driving arrest, but generally need a warrant for a blood test. If you're facing a real situation, talk to a lawyer in your state.

Can you buy the breathalyzer police use?

Some of the handheld models police use are sold to businesses and, in some cases, to the public, usually through professional suppliers. They cost more than consumer units, typically several hundred dollars or more, and need regular calibration. Evidential instruments are a different story. They're expensive, sold to agencies and labs, and need a maintenance program around them. They aren't a realistic personal purchase.

For most people, a good consumer fuel-cell breathalyzer is the sensible option. It uses the same basic sensor type as many police handhelds, without the professional price tag. That's why the main button on this page goes to the AlcoMate AL9000, a fuel-cell unit, with the Alcoscan AL2500 as a cheaper alternative. Check each product listing for its sensor type, accuracy claims and calibration schedule before you buy.

How personal breathalyzers compare

A personal fuel-cell unit and a police PBT won't always give the same number, even used on the same breath. Calibration, sensor age, how hard and long you blow, and timing after your last drink all move readings. Treat your own breathalyzer as a guide, not a prediction of what a police device will show.

Getting a reading you can trust from your own unit

1. Wait at least 15 to 20 minutes after your last drink, food, cigarette or mouthwash, the same way police do, so mouth alcohol doesn't inflate the result.
2. Blow steadily for as long as the instructions say. Short puffs usually read low.
3. Test at room temperature. Very cold or hot conditions can affect sensors.
4. Keep it calibrated on the maker's schedule. Fuel cells drift with use and age.
5. Retest after a few minutes if a reading seems off.
6. Remember BAC can still be rising for a while after you stop drinking, especially if you drank quickly or on an empty stomach.

Even a perfect personal reading below the legal limit doesn't mean you're safe to drive. Impairment starts well below 0.08, and commercial drivers and drivers under 21 face much lower limits.

Myths about beating a police breathalyzer

You'll find plenty of "tricks" online. They don't work, and some make things worse:

• Pennies, mints and gum don't fool a modern sensor. Some breath fresheners contain alcohol and can raise a reading.
• Breathing tricks don't help. Instruments check the sample's volume and flow, and officers are trained to spot irregular samples.
• Mouthwash before the test can push a reading up, not down. That's exactly what the waiting period is for.
• Coffee or water doesn't lower your BAC. Only time does, at roughly 0.015 per hour on average, and that varies by person.

The only reliable way to pass a breath test is not to drive after drinking. Plan a ride before the night starts.

Mistakes that make breath readings confusing

• Testing right after a drink and getting a scary-high number from mouth alcohol, then a much lower one later.
• Trusting a cheap keychain unit that hasn't been calibrated in years.
• Comparing your device's number to a police printout and expecting a match.
• Forgetting that BAC rises for a while after the last drink.

Where breath tests fit with other alcohol tests

Breath tests measure alcohol in your system right now. Blood tests do too, more directly. Urine tests for alcohol, especially EtG tests, look back further, often a day or more after drinking. Police impaired-driving cases mostly rely on breath and blood. Workplaces and treatment programs may use EtG urine testing. If you want the breath-vs-blood angle in detail, see our page on breathalyzer vs blood test results.

If drinking is becoming a problem

If you're worried about your drinking, or someone else's, the SAMHSA National Helpline is free, confidential and open 24/7 at 1-800-662-4357. If someone is in crisis or thinking about self-harm, call or text 988 for the Suicide and Crisis Lifeline.

Bottom line

Police use handheld fuel-cell units at the roadside to screen, and stricter infrared evidential instruments, usually at the station, for the reading that counts as evidence. The brands come from a small group of makers approved through NHTSA lists and state programs, and the process around the test, from the waiting period to calibration checks, matters as much as the device. For personal use, a calibrated fuel-cell breathalyzer is the closest match to what police carry, but it's for awareness only. The only safe plan is not to drive after drinking.

Information only, not legal or medical advice. Personal breathalyzers are not evidential devices and are not a substitute for DOT, federal, court-ordered or military testing.