Do police need probable cause to arrest me for DUI in Nevada?

Under Nevada’s “search and seizure” laws, law enforcement officers must have:

• Reasonable suspicion to pull you over or investigate you for drunk driving, and
• Probable cause to arrest you for a Nevada DUI.¹

Technically “reasonable suspicion” and “probable cause” are two distinct standards. In practice, however, they are quite similar.

“Reasonable suspicion” prevents you from being pulled over or arrested for no reason, an improper reason (such as your race) or a mere hunch. It means that there must be specific facts that lead a law enforcement officer to suspect that you are committing or have committed a traffic infraction or a crime.²

“Probable cause” for an arrest is a slightly higher standard. In the context of a DUI arrest, it means that a reasonable and cautious officer has a rational basis to believe that:

• You are too drunk or stoned to drive a vehicle safely (driving with impairment), or
• Your blood alcohol concentration (BAC) is above the legal limit (.08% or higher).³

Common ways an officer can show probable cause are preliminary DUI breath tests and field sobriety tests. But if the officer had no reasonable suspicion to administer the tests in the first place, the test results are inadmissible. And so is any evidence based on them – such as an evidentiary DUI blood test or DUI breath test.

Lack of probable cause can be a powerful Nevada DUI defense. If your traffic stop or arrest was illegal, your Nevada DUI defense lawyer can file a motion to suppress the evidence. And if the judge grants the motion to suppress, it will usually result in a dismissal of the charges or lead to a plea bargain to lesser charges in your DUI case.

To help you better understand how probable cause and reasonable suspicion affect DUI cases, our Las Vegas DUI lawyers will answer the following questions:

• 1. When can the Nevada police pull me over?
• 2. Do the police need reasonable suspicion to start a Nevada DUI investigation?
• 3. Do the police need probable cause to arrest me for Nevada DUI?
• 4. How do I challenge a Nevada DUI for lack of probable cause / reasonable suspicion?

1. When can the Nevada police pull me over?

In order to pull over a motorist for driving under the influence of alcohol or drugs, a Nevada law enforcement officer must have reasonable suspicion of criminal activity. The crime does not necessarily have to be driving under the influence. Any potential traffic infraction or violation is enough – even expired tags. As long as the officer can point to a valid reason for stopping your motor vehicle, the reasonable suspicion requirement is usually satisfied.

An exception is a DUI checkpoint. The U.S. Supreme Court has held that sobriety checkpoints do not violate the Fourth Amendment as long as they conform to certain standards of fairness and objectivity.⁴ Reasonable suspicion is not required.

2. Do the police need reasonable suspicion to start a Nevada DUI investigation?

In a Nevada DUI case, the next step after a traffic stop or a sobriety checkpoint is the DUI investigation.

With each phase of the DUI– the stop, the investigation and then a possible arrest—there is a higher standard for proceeding. For instance, if you are driving with a broken taillight, it does not necessarily follow that you are under the influence.

Before they begin a DUI investigation, Nevada law enforcement officers must have a reasonable suspicion that you are under the influence. Reasons why an officer might reasonably suspect you of DUI include (but are not limited to):

• An erratic driving pattern (such as weaving, swerving, driving too slowly, making wide turns, and other traffic violations);
• You fumble when producing your license and registration;
• Your speech is slurred;
• You admit that you have been drinking or at a bar;
• There are drugs, drug paraphernalia or alcohol visible inside your car; and/or
• You exhibit physical symptoms of inebriation (such as bloodshot eyes and the odor of alcohol or marijuana).

Police who have reasonable suspicion to pull over drivers for DUI may ask them to perform field sobriety tests.

If the peace officer reasonably suspects that you are a drunk driver, he or she may detain you for an investigation. A Nevada DUI investigation typically involves:

• Questions about where you have been and whether you have been drinking or using drugs;
• A Nevada preliminary breath test (PBT) on a handheld breathalyzer;
• One or more field sobriety tests (FSTs);⁵ and/or
• (If you consent — which we recommend you do not do) a search of your vehicle.

(See our article about the no-driving defense in Nevada DUI law.)

3. Do the police need probable cause to arrest me for Nevada DUI?

The standard required for an officer to arrest you for DUI in Nevada is higher than that for a traffic stop or an investigation.

An officer must have probable cause to make a Nevada DUI arrest.

This means an arresting officer must be able to articulate the exact facts that led him or her to reasonably believe you were DUI. Such “facts” might include:

• You blew an illegal breath alcohol level on the preliminary breath test;
• You performed poorly on FSTs;
• Drugs or alcohol were in the car; and/or
• You exhibited distinct signs of intoxication.

The officer won’t necessarily explain to you at the time of your arrest the basis for probable cause. But it should be contained in the police report. The officer must be able to convince the court that the arrest was lawful and reasonable under the “probable cause” standard.⁶

4. How do I challenge a Nevada DUI for lack of probable cause / reasonable suspicion?

Your Nevada DUI criminal defense attorney can file a motion to suppress any evidence that was obtained if your traffic stop, DUI investigation and/or DUI arrest was not based on reasonable suspicion or probable cause.

A motion to suppress evidence is based on a legal doctrine known as the “fruit of the poisonous tree.” This doctrine prevents the police from using illegal evidence to “bootstrap” their way into good evidence.

If your traffic stop or DUI investigation was “poisonous,” any evidence obtained as a result is poisonous, too, and subject to suppression. Whatever evidence the judge suppresses may not be used against you.

Thus if your Nevada DUI lawyer can convince the judge that there was no reasonable basis for your stop, investigation and/or arrest, your DUI charges could be reduced or even dismissed.

You should be aware, however, that judges are usually reluctant to suppress evidence for lack of probable cause in Nevada DUI cases. However, it often makes sense to file a motion anyway. As Las Vegas DUI defense lawyer Michael Becker explains:

“A motion to suppress evidence presents an opportunity to cross-examine the arresting officer in a Nevada DUI case. A good Nevada DUI defense lawyer can often discover weaknesses in the district attorney’s case and use them to negotiate reduced charges or even get them dismissed outright.”

For further help…

Call our DUI/DWI law firm for legal advice and help with your case. Our DUI defense attorneys offer consultations.

Facing misdemeanor or felony DUI offense charges in Las Vegas or elsewhere in the state of Nevada? Our criminal defense lawyers invite you to contact us for a consultation on how we fight to protect your constitutional rights and save your driver’s license.

Our Las Vegas DUI lawyers know how to find weaknesses in the prosecutor’s case – including lack of reasonable suspicion and/or probable cause for a traffic stop and/or Nevada DUI arrest.

In California? Read our article on Probable Cause in California DUI Cases.

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