Preliminary Alcohol Screening (PAS) Devices

Read about how police use breathalyzers to determine if there’s probable cause for a DUI arrest.

By , Attorney
Facing a DUI? We've helped 115 clients find attorneys today.

There was a problem with the submission. Please refresh the page and try again
Full Name is required
Email is required
Please add a valid Email
Phone Number is required
Please enter a valid Phone Number
Zip Code is required
Please add a valid Zip Code
Description is required
By clicking "Find a Lawyer", you agree to the Martindale-Nolo Texting Terms. Martindale-Nolo and up to 5 participating attorneys may contact you on the number you provided for marketing purposes, discuss available services, etc. Messages may be sent using pre-recorded messages, auto-dialer or other automated technology. You are not required to provide consent as a condition of service. Attorneys have the option, but are not required, to send text messages to you. You will receive up to 2 messages per week from Martindale-Nolo. Frequency from attorney may vary. Message and data rates may apply. Your number will be held in accordance with our Privacy Policy.

You should not send any sensitive or confidential information through this site. Any information sent through this site does not create an attorney-client relationship and may not be treated as privileged or confidential. The lawyer or law firm you are contacting is not required to, and may choose not to, accept you as a client. The Internet is not necessarily secure and emails sent through this site could be intercepted or read by third parties.

To lawfully arrest a motorist for DUI, an officer must have probable cause to believe the person was driving while under the influence of drugs or alcohol. Officers often use field sobriety tests (FSTs) and breathalyzers to make this determination. The breathalyzers officers use to assess whether there's probable cause to arrest a driver for DUI are called "preliminary alcohol screening" (PAS) or "portable breath test" (PBT) devices.

(The more accurate breathalyzers that police use to measure breath alcohol concentration (BAC) after a DUI arrest are called "evidential breath test" (EBT) machines.)

What Are PAS Devices?

PAS devices are small handheld machines that measure BAC. These portable breathalyzers give police a quick and easy way to estimate how much a motorist has been drinking. But PAS machines typically aren't as reliable or precise as EBT devices.

One main difference between PAS and EBT breathalyzers is the technology they use to measure BAC. Most PAS devices use semiconductor sensors, whereas EBT machines typically measure breath alcohol with more accurate fuel-cell or infrared sensors.

Generally, EBT results are admissible in court to prove a defendant's BAC. On the other hand, many states don't allow prosecutors to use PAS results to prove a driver's BAC.

Are Drivers Required to Take PAS Tests?

Without probable cause. Generally, police can't require a driver to take a PAS test without probable cause of driving under the influence.

With probable cause but pre-arrest. The laws of some states require that motorists comply with pre-arrest PAS testing if the officer has probable cause to suspect drunk driving. In other states, including California, drivers are free to refuse an officer's request to take a pre-arrest PAS test. California law additionally requires police to inform drivers of their right to refuse PAS testing.

(Every state has implied consent laws that generally require all motorists arrested for driving under the influence to submit to chemical testing—typically a blood, breath, or urine test.)

Talk to an Attorney

DUI laws are complicated and constantly changing. If you've been arrested for driving under the influence, get in touch with an experienced DUI attorney in your area. A local DUI lawyer can explain the laws in your state, analyze the facts of your case, and let you know if there are any possible defenses.

FACING A DUI?
Talk to a DUI Defense attorney
We've helped 115 clients find attorneys today.
There was a problem with the submission. Please refresh the page and try again
Full Name is required
Email is required
Please add a valid Email
Phone Number is required
Please enter a valid Phone Number
Zip Code is required
Please add a valid Zip Code
Description is required
By clicking "Find a Lawyer", you agree to the Martindale-Nolo Texting Terms. Martindale-Nolo and up to 5 participating attorneys may contact you on the number you provided for marketing purposes, discuss available services, etc. Messages may be sent using pre-recorded messages, auto-dialer or other automated technology. You are not required to provide consent as a condition of service. Attorneys have the option, but are not required, to send text messages to you. You will receive up to 2 messages per week from Martindale-Nolo. Frequency from attorney may vary. Message and data rates may apply. Your number will be held in accordance with our Privacy Policy.

You should not send any sensitive or confidential information through this site. Any information sent through this site does not create an attorney-client relationship and may not be treated as privileged or confidential. The lawyer or law firm you are contacting is not required to, and may choose not to, accept you as a client. The Internet is not necessarily secure and emails sent through this site could be intercepted or read by third parties.

How It Works

  1. Briefly tell us about your case
  2. Provide your contact information
  3. Choose attorneys to contact you