Fighting a DUI Charge: Did Police Violate Your Constitutional Rights?

A recent decision by the Superior Court of Pennsylvania demonstrates that a driver’s impairment (or lack thereof) isn’t the only issue at play when fighting a DUI charge. When applicable, another avenue for fighting a DUI charge is to challenge the constitutionality of the underlying traffic stop.

A Well-Being Check

In Commonwealth v. Thimons, a police officer was doing a routine check of closed businesses at 1:00 a.m., looking for suspicious activity, when he observed an SUV travel from behind a building, enter the building’s front parking lot, and park in a parking space. The officer decided to check on the well-being of the driver and pulled into a parking space behind the SUV, but did not block it in. He then activated the red and blue lights on his police cruiser.

After approaching the SUV and talking to the driver, the officer believed she was impaired by alcohol. A backup officer ran a check on the driver’s license information and learned that her license had been suspended for DUI. The first officer had the driver perform three field sobriety tests. Results of two of the tests indicated impairment, while results of the third test were inconclusive.

The driver subsequently was charges with DUI — general impairment, DUI — highest rate of alcohol, driving while operating privilege is suspended or revoked, and driving with an open alcoholic beverage container. Prior to trial, the driver sought to suppress the evidence against her, arguing that her traffic stop and subsequent detention by law enforcement was illegal.

The trial court denied the driver’s request to suppress the evidence, and she was convicted on all charges.

The driver appealed to the Superior Court of Pennsylvania.

Investigative Detention

On appeal, the Superior Court sided with the driver, finding that the traffic stop violated both her state and federal constitutional rights to be free from unreasonable searches and seizures because the officer did not possess a reasonable suspicion to conduct an investigative detention of the driver.

In short, there are three types of interactions between citizens and police: mere encounter, investigative detention, and custodial detention. The Superior Court set forth the definition of each:

A mere encounter between police and a citizen need not be supported by any level of suspicion, and carr[ies] no official compulsion on the part of the citizen to stop or to respond. An investigatory stop, which subjects a suspect to a stop and a period of detention … requires a reasonable suspicion that criminal activity is afoot. A custodial search is an arrest and must be supported by probable cause.

Here, the court found that the stop was an investigative detention because the officer’s activation of the red and blue lights on his police cruiser meant that the driver was not free to leave. Accordingly, to be legal, the officer needed to have a reasonable suspicion that a crime was afoot.

The court found that no reasonable suspicion existed:

[The officer’s] testimony points to no specific or articulable facts indicating that he possessed the reasonable belief that criminality was afoot. [The officer] did not identify any crime (e.g., DUI, possession or distribution of controlled substances, burglary, etc.) that he believed [the driver] may have committed or may have been in the process of committing. All the record indicates is that at approximately 1:00 a.m., [the driver] drove her vehicle behind a closed business and parked her car in an empty parking lot in front of that business.


The ruling is good news for the driver, as without the evidence obtained from the traffic stop, the Commonwealth most likely will not be able to proceed with its case. For the rest of us, it is a reminder that DUI convictions can rise and fall based upon police conduct alone, without getting into issues of driver impairment. As always, if you have been arrested for DUI, we recommend that you consult with a qualified DUI attorney immediately to ensure that your legal rights are protected.