What is reasonable suspicion for a DUI stop?

Except for DUI checkpoints and roadblocks, police officers in Pennsylvania are only allowed to stop motorists when they have a reasonable suspicion that the motorists have committed violations or have engaged in criminal activities.

If an officer has a reasonable suspicion that you have committed a crime or a traffic violation, the officer can stop and briefly detain you to conduct a limited investigation.

If the officer suspects that you might be driving under the influence of alcohol or drugs after stopping you, the officer might then ask you to perform field sobriety tests and submit to a preliminary breath test.

If you are unsure whether the officer had a reasonable suspicion to support your stop, the legal team at DiCindio Law can review the evidence and provide you with some guidance.

What is reasonable suspicion?

Reasonable suspicion is a legal standard that requires officers to have an objectively reasonable basis for believing that you might have committed a violation or crime.

It cannot be an inarticulable hunch. In other words, an officer can’t pull you over simply because he or she thinks that you look suspicious without other objective indicators that you have committed a traffic offense or crime. An officer can stop you for nearly any type of violation, including faulty equipment, speeding, erratic driving, or others.

Reasonable suspicion for performing a DUI stop might be based on any of the following types of observations:

  • Crossing the centerline
  • Making an illegal turn
  • Weaving in and out of your lane
  • Driving on the wrong side of the road
  • Driving very slowly or erratically
  • Almost hitting other vehicles or objects
  • Braking frequently
  • Stopping in the road for no reason

An officer can pull you over for anything that the officer reasonably believes is a sign that you might be driving under the influence of alcohol or drugs.

An officer can also pull you over based on a reasonable suspicion that you committed a different offense and subsequently investigate further if he or she makes observations that lead him or her to suspect impairment.

An officer can sometimes form a reasonable suspicion that you were driving drunk even if he or she did not see you driving. For example, an officer might ask you to perform field sobriety tests after an accident or if you were found asleep behind the wheel of your car.

How does reasonable suspicion compare with probable cause?

Having reasonable suspicion allows a police officer to stop and detain a motorist temporarily so that the officer can investigate whether the motorist committed a traffic offense or crime.

The officer must have more evidence to develop probable cause before he or she can place the motorist under arrest. Probable cause means that the officer has sufficient evidence to believe that the person has likely committed a crime, justifying an arrest.

During a DUI stop, an officer might develop probable cause through his or her observations of the driver and the driver’s performance on field sobriety tests or the results from a preliminary breath test.

Probable cause is a standard used by judges when they evaluate arrests. If the facts support a reasonably objective belief that the person committed a crime, probable cause will be found.

After an officer has a reasonable suspicion that a motorist has committed a traffic offense, he or she will work to develop additional evidence to support probable cause to arrest the driver for a DUI.

How to argue the officer lacked reasonable suspicion or probable cause

It can be challenging to argue that an officer did not have reasonable suspicion to stop you or probable cause to arrest you. However, police officers sometimes make mistakes.

If an officer made mistakes in how you were pulled over or in his or her investigation, your charges might be dismissed.

Your attorney will carefully analyze the reason why the officer stopped your vehicle to determine whether he or she had a reasonable suspicion that you committed a traffic offense or other crime.

If the officer did not have a reasonable suspicion, all of the evidence that the officer gathered following the stop will be inadmissible. This means that your charges will be dismissed.

After an officer stops you, he or she will likely make observations to determine whether you might be driving under the influence of alcohol or drugs.

Some of the things that an officer might look for include the following:

  • Acting suspiciously
  • Having trouble getting your license or registration
  • Odor of alcohol on your breath
  • Bloodshot, watery eyes
  • Slurred speech
  • Statements that you make

If the officer makes observations that lead him or her to believe that you might be intoxicated, he or she will include all of the observations that he or she makes in the police report.

For example, if an officer pulls you over after seeing you weave in and out of your lane, the officer might ask you if you have had any alcohol.

He or she might then develop probable cause based on the observations that are made, your statements, your performance on the field sobriety tests, and results on the preliminary breath test.

If you are arrested for a DUI, you cannot refuse to submit to a post-arrest breath or blood test under Pennsylvania’s implied consent law. If you refuse to submit to a test, you will face civil penalties. If you are convicted of a DUI offense, a refusal will result in harsher penalties.

Contact Our DUI Law Firm in West Chester, PA

If you are facing criminal charges and need legal help, contact the West Chester, PA DUI lawyers at DiCindioLaw, LLC to schedule a free initial consultation.

DiCindio Law, LLC

29 S Walnut St
West Chester, PA 19382
(610) 430-3535


***This blog article is made available by the law firm publisher for educational purposes and to provide general information, not to provide specific legal advice. By reading, you understand that there is no attorney client relationship between you and the publisher. The above listed information does not include the entire crimes code, annotations, amendments or any recent changes that may be relevant. The information provided is for informational purposes only and may not reflect the most current legal developments. These materials are not intended, and should not be taken, as legal advice on any particular set of facts or circumstances. Please contact DiCindio Law, LLC for a consultation and to discuss what law is relevant to your case. ***