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Probable Cause in DUI Cases


A criminal charge is a serious case because it can potentially take away a person’s freedom, but criminal prosecution is a necessity in every society. However, those who hold power or made a horrible mistake can easily have someone innocent thrown in jail. Therefore, “probable cause” is a requirement for most criminal charges to protect a person’s rights, but what is probable cause exactly? Here’s the excerpt from the Fourth Amendment detailing probable cause:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

In layman’s terms, the police requires a good reason behind their suspicion (reasonable suspicion) before someone is issued a warrant for search or arrest. There are some exceptions however, as they can immediately arrest or search someone if they observe someone committing or allegedly committing a crime.

How is probable cause related to DUI?

When it comes to DUI, establishing probable cause is a requirement before the alleged drunk driver is charged with driving under the influence. The police cannot simply stop you at any time and perform searches or tests on you, as long as reasoning is not enough for doing it in the first place. Let’s take a look at some common scenarios at how probable cause relates to DUI:

Traffic Stops

Like we mentioned earlier, you cannot be stopped at any time just because the police only think you look suspicious, they have to give a good reason behind the stop in the first place. This is the reason they cannot just randomly stop motorists unless they see the driver doing something suspicious or received erratic driving reports about that particular driver. Your Las Vegas DUI lawyer can file a motion to suppress a traffic stop by arguing that the traffic stop lacked probable cause. If successful, the evidence collected after the unwarranted stop can be suppressed, which is likely to dismiss the case.

Breath, Blood, and Urine Tests & Field Sobriety Tests

At the same time, they cannot perform tests on you if they do not have probable cause. Since these tests often stem from stops, they also require a reasonable suspicion for the stop too. Meanwhile, field sobriety tests are also used to establish probable cause, but most defendants did not know they can refuse them. Read why refusing FST are a good idea.


The police cannot search your car without a warrant, unless it is related to the crime. For example, they cannot search your vehicle if they only pulled you over because you ran a stop sign. This is important because a simple traffic offense (often misdemeanors), can become a felony if probable cause did not protect the defendant from these searches.

In any case, your Las Vegas criminal defense attorney will be able to explain to you if they had probable cause, just make sure to give them all the details that led up to the arrest.

For more information about DUI, click here.

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