Probable cause is one of the most misunderstood concepts in criminal law. Many people believe that as long as an officer “feels” something is wrong, they can stop, search, or arrest you. But the law sets a much higher standard. Probable cause isn’t about a hunch—it’s about having solid evidence that a crime has occurred or is occurring.
In this blog, we’ll explore what probable cause really means, how it affects DUI and criminal charges in Tennessee, and why it’s a critical issue when building a defense. Whether you’re facing charges or just want to understand the law, knowing how probable cause works can help protect your rights and shape the outcome of a criminal case.
What Is Probable Cause?
Probable cause is more than just a “gut feeling.” It’s a legal standard that requires law enforcement to have a valid reason, based on facts or evidence, to believe that a crime has been committed. In simple terms, it means there must be enough information to justify an arrest, search, or seizure. More specifically however, probable cause requires enough evidence to warrant a prudent or reasonable person to believe the crime has been committed. This standard of proof is more than reasonable suspicion which requires specific and articulable fact and more than a mere hunch. Our attorneys often argue that officers lacked reasonable suspicion, the lower standard, let alone the heightened standard of probable cause.
The concept of probable cause is rooted in the Fourth Amendment of the U.S. Constitution, which protects citizens against unreasonable searches and seizures. In Tennessee, this principle applies to every stage of a criminal case, from traffic stops to searches of your home or vehicle. For police officers to make a lawful arrest, search your property, or obtain a warrant, they must show concrete facts that support their actions.
Example Scenarios:
- During a traffic stop, an officer might observe you swerving between lanes or speeding. These observations can serve as reasonable suspicion or probable cause to pull you over. If, during the stop, the officer detects the odor of alcohol, sees open containers and slurred speech, that evidence can further establish probable cause for a DUI investigation. However, your attorney should never overlook any detail and meticulously question officers about the alternative reasons for why you make look or sound a certain way, and the alternative causes. Similarly, an odor only shows consumption, but not evidence of impairment which is another important factor to be addressed.
- In a drug investigation, if officers witness you exchanging small packages in a known drug area, they may have probable cause to search your vehicle for illegal substances if you appear nervous and other factors are potentially present.
Probable cause is crucial because it sets the legal bar for when law enforcement can supersede your rights. Without it, any evidence gathered might be deemed inadmissible in court, significantly impacting the outcome of your case.
Probable Cause vs. Reasonable Suspicion
What Is Reasonable Suspicion?
Reasonable suspicion is a lower standard than probable cause. It allows law enforcement to briefly stop or detain someone if they have specific, articulable facts suggesting that criminal activity may be afoot. Unlike probable cause, it doesn’t require concrete evidence—just a rational suspicion based on observable behavior. For instance, an odor of alcohol and failure to maintain lane potentially may result in reasonable suspicion, depending on the strength of the officer’s testimony, whereas probable cause generally requires additional evidence such as field sobriety testing.
Key Differences:
- Probable Cause: Requires specific facts or evidence indicating that a crime has occurred, is occurring, or will occur. It’s the standard needed for arrests, searches, or obtaining a warrant.
- Reasonable Suspicion: Based on a lower threshold of evidence. It allows an officer to conduct brief stops or investigations, such as pulling over a vehicle for erratic driving or conducting a “stop and frisk” if someone appears to be carrying a concealed weapon.
Examples:
- Reasonable Suspicion: An officer notices a car weaving in and out of lanes late at night. The erratic driving provides reasonable suspicion for the officer to pull the car over for a traffic violation and ask if the individual has been drinking.
- Probable Cause: Once the car is stopped, if the officer smells alcohol on the driver’s breath, sees open containers in the vehicle, or observes the driver failing a field sobriety test, these facts establish probable cause for a DUI arrest.
These two standards of proof are seen in all felony and misdemeanor criminal defense cases and your attorney should be well versed in cross-examinations and articulating the information in a way that is advantageous to your defense in your criminal case.
Why This Matters:
The distinction between probable cause and reasonable suspicion is crucial because it determines what actions law enforcement can legally take. Without probable cause, any search or arrest could be challenged in court. Similarly, if an officer conducts a stop without reasonable suspicion, any resulting evidence could be thrown out and it may result in a dismissal or favorable reduction through negotiations.
How Long Can Police Detain You Without Probable Cause?
Under the reasonable suspicion standard, police can stop and briefly detain you for investigative purposes, but there are limits to how long they can hold you without probable cause. For example, during a traffic stop, an officer may ask for your license and registration, inquire about your activities, and, if needed, conduct a brief investigation, like a field sobriety test.
However, the detention must remain temporary. If the officer cannot develop probable cause within a reasonable time frame, they are generally required to let you go. The exact duration considered “reasonable” can vary, but courts often scrutinize whether the officer’s actions were proportional to the suspected offense and whether they acted diligently to either confirm or dispel their suspicions.
If law enforcement detains you beyond a reasonable period without establishing probable cause, any evidence gathered during that extended detention may be challenged and potentially suppressed in court.
Probable Cause in DUI Cases
In Tennessee, DUI stops are among the most common situations where probable cause comes into play, beginning with the initial traffic stop. To pull you over, an officer needs reasonable suspicion, such as observing you swerving, speeding, or running a stop sign. However, reasonable suspicion alone is not enough to make an arrest. For a DUI arrest, the officer must develop probable cause during the stop.
Building Probable Cause During the Stop:
Once you’re pulled over, the officer will look for further evidence to establish probable cause. Here are some common signs they may use:
- Observations: Bloodshot eyes, slurred speech, unsteadiness on feet and the smell of alcohol on your breath can all be used to build probable cause.
- Field Sobriety Tests: The officer may ask you to perform field sobriety tests (like walking in a straight line or standing on one leg). If you fail these tests, it can add to the probable cause for your arrest.
- Breathalyzer Tests: Preliminary breath tests during the stop can provide an officer with additional evidence to support probable cause. However, keep in mind that in Tennessee, you have the right to refuse these roadside tests. Most of the time PBT’s are not used in Tennessee because the results are unreliable and deemed inadmissible. The breath tests at the station may be admissible but there are many issues with breath testing that your criminal defense attorney should be familiar with to attempt to suppress such evidence.
Probable Cause for Breathalyzer and Blood Tests:
After you’re arrested for DUI, the officer will usually request a formal breath or blood test to measure your blood alcohol concentration (BAC). For this request to be legal, there must be probable cause established during the stop, based on the officer’s observations, field sobriety tests, or preliminary breath test results.
Probable Cause in Criminal Defense Cases
Probable cause is not only critical in DUI cases—it plays a central role in many criminal defense situations in Tennessee. Whether it’s a drug possession case, theft, felony drug case, or a search of your property, law enforcement must meet the probable cause standard to take certain actions. Understanding how probable cause works in these contexts can reveal potential violations of your rights.
Arrests and Probable Cause:
For an officer to make an arrest, they need probable cause to believe that you have committed a crime. This means they must have specific evidence or facts that point to your involvement in the alleged offense. For example:
- Drug Possession: If an officer sees a small bag of what appears to be illegal drugs in plain view inside your car, this observation can provide probable cause for an arrest. Plain view searches require that the illegality of the substance is immediately apparent to the officer.
- Theft: If you’re caught on surveillance camera leaving a store with unpaid merchandise, the footage serves as probable cause for law enforcement to arrest you for theft.
Search Warrants and Probable Cause:
Probable cause is also essential when law enforcement seeks to search your property. To obtain a search warrant, officers must present specific facts or evidence to a judge, demonstrating that it’s likely a crime has occurred and that evidence related to the crime will be found in the place they want to search. For example:
- Home Searches: If police suspect drug manufacturing in a home, they must show evidence—like reports of unusual chemical odors or witness statements—to obtain a search warrant.
- Vehicle Searches: While a search warrant is often not required for vehicle searches, officers must still have probable cause to believe the vehicle contains evidence of a crime. For instance, if an officer sees drug paraphernalia on the passenger seat during a traffic stop, this sighting could establish probable cause for a vehicle search.
Warrantless Searches and Probable Cause:
In some cases, officers conduct searches without a warrant. However, they must still have probable cause. Common situations include:
- Consent Searches: If you give an officer permission to search your property, they don’t need a warrant. However, you have the right to refuse consent. If you refuse, officers must then demonstrate probable cause to a judge to obtain a warrant.
- Plain View Doctrine: If illegal items are in plain sight, such as drugs visible on a car’s dashboard, the officer has probable cause to conduct a search without a warrant.
Challenging Probable Cause in Court
If you believe your rights were violated due to a lack of probable cause, challenging it in court can be a powerful defense strategy. Successfully proving that law enforcement did not have proper grounds for a stop, search, or arrest can result in key evidence being thrown out—and in some cases, may lead to a dismissal of the charges against you.
Pre-Trial Motions to Suppress Evidence:
One of the most effective ways to challenge probable cause is through a motion to suppress evidence. Your attorney can file this motion before the trial, arguing that the evidence obtained by law enforcement should be excluded because it was gathered without valid probable cause. If the court agrees, any evidence obtained as a result of the illegal stop, search, or arrest will be deemed inadmissible. This can greatly weaken the prosecution’s case.
How Attorneys Challenge Probable Cause:
A skilled defense attorney will thoroughly investigate the circumstances surrounding your arrest or search to identify weaknesses in the officer’s justification for their actions. Here are some common angles attorneys explore when challenging probable cause:
- Lack of Specific Facts: An officer’s vague or generalized suspicions, such as “the driver seemed nervous,” are not enough to establish probable cause. Your attorney may argue that the officer’s observations did not meet the legal standard required.
- Flawed Field Sobriety Tests: In DUI cases, your attorney might argue that the officer improperly conducted field sobriety tests, resulting in an invalid basis for probable cause.
- Illegal Search: If a search was conducted without a warrant or the officer lacked clear evidence to justify it, your attorney can argue that the search violated your Fourth Amendment rights.
- No Observable Evidence: If you were arrested without any clear, observable evidence of a crime (such as failing to show signs of impairment during a DUI stop), your attorney may argue that the officer did not have probable cause for the arrest.
If the court rules that there was no probable cause for your arrest, stop, or search, the evidence obtained as a result is typically deemed inadmissible. This could include critical evidence like breathalyzer results in a DUI case or seized items in a drug possession case. When key evidence is suppressed, the prosecution’s case may weaken to the point where they have no choice but to dismiss the charges or negotiate a favorable plea deal.
Protect Your Rights With Barnes & Fersten
If you believe your arrest stemmed from a lack of probable cause, you deserve a fair defense in court. At Barnes & Fersten, we have a proven track record defending DUI and criminal cases in Tennessee, and we know how to scrutinize police investigations to protect your rights. Our experienced attorneys will carefully review your case, identify potential violations of your rights, and build a strong defense strategy to challenge any unlawful actions taken against you.
Don’t wait—fill out our contact form or call us at 865-805-5703 for a free consultation. Let us help you protect your rights and fight for the best possible outcome in your case.
Attorney At Law, Managing Partner
Brandon D. Fersten is an esteemed Knoxville attorney practicing DUI, criminal defense, and juvenile law. Known for his empathetic approach and commitment to his clients, he brings a record of favorable case outcomes including dismissals and not guilty verdicts at jury trials resulting in Brandon being recognized as one of the “Top 40 Under 40” in Criminal Defense, U.S. News’ Best Lawyers: “Ones to Watch,” and Super Lawyers’ “Rising Stars”. Brandon’s professional accolades, combined with his passion for justice, position him as a reliable criminal defense advocate in the East Tennessee legal landscape, including Knox County, Blount County, Sevier County, Roane County, Anderson County, and Cumberland County.
