{"id":286650,"date":"2016-07-20T16:36:13","date_gmt":"2016-07-20T21:36:13","guid":{"rendered":"https:\/\/content.findlaw-admin.com\/ability-law\/dui\/arrests\/what-is-a-pas-device.html"},"modified":"2026-04-09T12:35:19","modified_gmt":"2026-04-09T17:35:19","slug":"what-is-a-pas-device","status":"publish","type":"page","link":"https:\/\/www.findlaw.com\/dui\/arrests\/what-is-a-pas-device.html","title":{"rendered":"What Is a Preliminary Alcohol Screening (PAS) Device?"},"content":{"rendered":"\n
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What Is a Preliminary Alcohol Screening (PAS) Device?<\/h1>\n\n
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\n By Hannah Hilst<\/a> | Legally reviewed by Meagan Neil, Esq.<\/a>\n | Last reviewed\n
\n \n <\/i>\n Legally Reviewed\n <\/summary>\n\n
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This article has been written and reviewed for legal accuracy, clarity, and style by FindLaw\u2019s team of legal writers and attorneys<\/a> and in accordance with our editorial standards<\/a>.<\/em><\/p>\n\n <\/div>\n <\/details>\n\n

\n \n <\/i>\n Fact-Checked\n <\/summary>\n\n
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The last updated date refers to the last time this article was reviewed by FindLaw or one of our contributing authors<\/a>. We make every effort to keep our articles updated. For information regarding a specific legal issue affecting you, please contact an attorney in your area<\/a>.<\/em><\/p>\n\n <\/div>\n <\/details>\n<\/section>\n\n\n

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A preliminary alcohol screening<\/span> (PAS) device<\/span> is a type of breath test<\/span> device<\/span>. Police officers<\/span> use a PAS device<\/span> to estimate a driver\u2019s blood-alcohol content<\/span> (BAC<\/span>). If the device indicates a BAC<\/span> level near or above the state\u2019s legal limit, the driver will face an arrest for drunk driving<\/span>. Challenging the PAS test and probable cause for the arrest<\/span>\u00a0is one possible DUI <\/span>defense<\/span> strategy<\/span>.<\/p>\n\n <\/div>\n\n\n\n

When police pull you over on suspicion of driving under the influence<\/span> (DUI), they can ask you to take a series of\u00a0field sobriety tests<\/span>. Their DUI investigation may involve observing basic motor skills, involuntary eye movements, and estimated blood-alcohol levels<\/span>.<\/p>\n

A law enforcement officer<\/span> typically uses a preliminary alcohol screening<\/span> device<\/span> to estimate a suspect\u2019s blood alcohol concentration<\/span>. These hand-held devices<\/span> aren\u2019t considered accurate enough to be used as the basis for criminal charges. Instead, breath alcohol <\/span>test<\/span> results<\/span> from PAS devices<\/span> can help establish\u00a0probable cause<\/span> for an arrest.<\/p>\n

This article discusses how the police use PAS devices<\/span>. It also explains how a PAS device<\/span> differs from the larger, more accurate tools often referred to by the brand name “Breathalyzer<\/span>.”<\/p>\n

You\u2019ll need to understand the legal significance of a PAS device<\/span> in your\u00a0DUI case<\/span>. A DUI defense<\/span> attorney<\/a> can review the evidence, including a breath test<\/span>, and explain your potential next steps.<\/p>\n

The Role of Breath Tests<\/span> at a DUI Stop<\/h2>\n

A PAS device<\/span> is a tool used by police to establish\u00a0probable cause<\/span><\/a>\u00a0for a DUI arrest<\/span> at the scene of a traffic stop<\/span>. It is often confused with its larger, more precise cousin, the\u00a0Breathalyzer<\/span>.<\/p>\n

Both are types of breath tests<\/span>. Both indirectly determine the amount of alcohol in a person\u2019s blood<\/span>. Still, a blood test<\/span> is the most accurate way of determining blood alcohol content<\/span><\/a>.<\/p>\n

How PAS Devices<\/span> Work<\/h3>\n

The hand-held PAS device<\/span> has a tube into which the suspect submits a breath sample<\/span>. The device then provides an instant estimate of the suspect\u2019s BAC<\/span>.<\/p>\n

Based on this estimate and other observations, the officer decides whether to make an\u00a0arrest<\/a>\u00a0for being under the influence of alcohol<\/span>. A positive preliminary <\/span>alcohol screening<\/span> test<\/span> result<\/span> isn\u2019t necessary for an arrest. In many states, it\u2019s also not admissible into evidence at trial for a DUI conviction.<\/p>\n

Are PAS Devices<\/span> Accurate?<\/h3>\n

In terms of accuracy, most states have determined that PAS devices<\/span> aren\u2019t reliable enough to be admissible as evidence<\/a>. States have made this decision through case law or statute. PAS devices<\/span> also aren\u2019t subject to the same stringent police standards as BAC<\/span>-testing instruments.<\/p>\n

For example, Illinois statute (625 ILCS 5\/11-501.5<\/a>) explicitly states that roadside testing with a PAS device<\/span> is only for determining probable cause<\/span>. The law states that suspects can refuse the test.<\/p>\n

But in Alaska, police can\u2019t ask a motorist<\/span> to submit to a preliminary BAC<\/span> test unless probable cause<\/span> has already been established.<\/p>\n

Some states allow the defense to offer evidence from preliminary tests involving a PAS device<\/span>. The evidence is admissible to show that testing was somehow defective or inaccurate.<\/p>\n

PAS Devices<\/span> vs. Breathalyzers<\/span><\/h2>\n

The larger, more accurate instruments used at the police station<\/span> are subject to strict procedures and\u00a0calibration<\/span> standards<\/a>. These instruments, known as Breathalyzers<\/span>, have safeguards to prevent false positives. They\u2019re generally considered quite accurate.<\/p>\n

It\u2019s difficult for a defense attorney to challenge the admissibility<\/span> of the results of a Breathalyzer<\/span> test. In contrast, PAS <\/span>test<\/span> results<\/span> are excluded in many states because they don\u2019t meet the high standards of reliability and accuracy.<\/p>\n

The PAS device<\/span> is one of several tools for determining whether a motorist<\/span> should be arrested for a DUI<\/a>. In contrast, the stationary breath screening instrument at the police station<\/span> is used to establish a criminal case against a defendant.<\/p>\n

Can I Refuse a PAS Test<\/span>?<\/h2>\n

Under most state implied consent laws<\/span>, you\u2019re not required to submit a breath sample<\/span> for analysis by a PAS device<\/span>. Implied consent laws<\/span> apply to the evidentiary BAC<\/span> test taken after an arrest. There are exceptions.<\/p>\n

Loss of driving privileges is a significant effect of many driving while intoxicated (DWI<\/span>) convictions. For instance, in California<\/span>, drivers under 21 can\u00a0lose their driver\u2019s license<\/span><\/a>\u00a0for one year if a PAS device<\/span> shows a BAC<\/span> of just 0.01%.\u00a0Florida law is similar<\/a>. It imposes 50 hours of public service (and license suspension until service is completed) for drivers under 21 who refuse to submit to a PAS test<\/span>.<\/p>\n

But suppose you decline to provide a breath sample<\/span> during a roadside field sobriety test<\/span><\/a>. If your case goes to trial, that fact can be used against you in court. This is true even if the test results<\/span> are inadmissible. The jury can see a refusal to take a breath or chemical test<\/span> as an attempt to evade arrest.<\/p>\n

Ask an Attorney About Fighting a DUI<\/h2>\n

Getting pulled over in your motor vehicle<\/span> and being arrested for a DUI is a stressful experience. You\u2019ll want to avoid making any mistakes that could hurt your defense.<\/p>\n

You have the right to a criminal defense<\/span> or DUI defense<\/span> attorney. Discuss the law and your rights, including the legal significance of a PAS device<\/span>, with an experienced\u00a0DUI attorney<\/span>\u00a0near you<\/a>. A DUI lawyer<\/span> can help educate you on DUI penalties, DUI probation<\/span>, and DUI laws.<\/p>\n\n\n\n

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