What do police officers look for when making vehicle stops for a suspected DUI?

The Pennsylvania DUI Association, along with the Department of Transportation and the Traffic Institute for Police Sciences, has formulated a list of signs that police officers are trained to look for on the roadways, which are deemed to be highly correlated to the possibility that a driver is under the influence. These cues and their corresponding probability that the operator is under the influence are:

  • Turning with a wide radius — 65%
  • Straddling center or lane marker — 65%
  • Appearing to be drunk – 60% (such as eye fixation, slouching in the seat, a tight grip on the steering wheel, erratic or obscene gesturing, keeping the face close to the windshield, protruding the head from the vehicle, or drinking inside the vehicle)
  • Almost striking an object or another vehicle — 60%
  • Weaving — 60%
  • Driving on other than the designated roadway — 55%
  • Swerving — 55%
  • Slow speed, more than 10 miles per hour below the speed limit — 50%
  • Stopping without cause in a traffic lane — 50%
  • Following too closely — 50%
  • Drifting — 50%
  • Tires on the center line or lane marker — 45%
  • Braking erratically — 45%
  • Driving into opposing or crossing traffic — 45%
  • Signaling inconsistently with driving actions — 40%
  • Slow response to traffic signals — 40%
  • Stopping inappropriately — 35%
  • Turning abruptly or illegally — 35%
  • Accelerating or decelerating rapidly — 30%
  • Driving at night with headlights off — 30%

When two or more cues are observed, 10 percentage points are added to the higher value. These cues do not necessarily establish, alone, probable cause for a DUI arrest or the basis for a vehicle stop. Just because the presence of one or more cues may attract a police officer’s attention, it doesn’t mean the officer automatically had the requisite reasonable suspicion to perform a vehicle stop.

Once the officer has stopped me, what clues are they looking for as they are speaking with me?

Again, there is a list of common indicia of intoxication which police officers are trained to look for during an interaction with someone suspected of DUI. They are:

  • Red, watery, glassy, and/or bloodshot eyes
  • Flushed face
  • Odor of alcohol on the breath or emanating from the car
  • Slurred speech
  • Fumbling with wallet trying to get license, registration, and insurance papers
  • Failure to comprehend the officer’s questions
  • Staggering when exiting the vehicle
  • Swaying/instability on feet
  • Leaning on car for support
  • Combative, argumentative, jovial, or other “inappropriate” attitude
  • Soiled, rumpled, disorderly clothing
  • Stumbling while walking
  • Disorientation as to time and place
  • Inability to follow directions

If I am stopped while driving my vehicle, do I have to answer the police officer’s questions?

A driver must answer basic identification questions and respond to requests to produce proof of license, registration, and insurance. However, beyond that, a driver is under no obligation to aid an officer’s investigation, be it for a DUI or any crime. Anything said can and most likely will be used against you in court.

Even if I don’t have to, should I answer the police officer’s questions?

If you are certain that the truthful answers to the questions will help you, such as if you have not been drinking or have not ingested any drugs whatsoever, then affirming so may expedite the process in your favor. However, lying about not drinking or ingesting drugs may provide what is known as “consciousness of guilt” evidence and damage your credibility as to other facts, as subsequent evidence may prove that the statement was a lie. A response such as “I only had two drinks” only serves to assemble probable cause for the officer to pursue further inquiry and perhaps lodge a DUI charge. Under most circumstances, the best response is to politely but firmly decline to answer the officer’s questions, ask if you are free to leave, and if not, to request an attorney. Refusing to answer questions that are potentially incriminating may not be used against you in court, as it is your constitutional right to do so.

Doesn’t the police officer have to read me my rights/Miranda warnings?

Miranda rights must be announced by an officer prior to questioning in the context of a custodial interrogation. A vehicle stop, if brief enough and if the circumstances support it, qualifies as an investigatory detention, rather than a custodial detention. Therefore, the questioning an officer performs in this context need not be preceded by Miranda warnings. Once an arrest is made for a crime, such as a DUI, the custody requirement for Miranda warnings is met, and questioning following that point must be preceded by the suspect being informed of his/her rights. Through both periods, one always has the right to remain silent as discussed earlier, regardless of whether Miranda rights were explained. If your Miranda rights were violated, the remedy is suppression of the evidence obtained as a result of the violation.

Do I have the right to an attorney when I am pulled over or stopped by a police officer?

The same way a police officer does not have to advise a suspect of Miranda rights during an investigatory detention, an individual does not have the right to an attorney until he/she is formally charged and/or arrested. The police may pull drivers over, ask them for information, ask for the performance of field sobriety tests, and conduct the investigative steps for a DUI without the presence of the suspect’s attorney. However, you still have the right to remain silent as explained throughout this passage.

What are field sobriety tests?

Field Sobriety Tests (FSTs) are a series of tests that police officers perform on the scene in the course of a DUI investigation. They were developed by the National Highway Traffic Safety Administration in an attempt to develop a somewhat reliable and consistent method to assess if an individual is under the influence. They are scored subjectively by the police officer, who should be noting his observations of the suspect’s ability to perform the tasks. The tasks themselves can include whatever the examining police officer requests, and can include examples such as reciting the alphabet, finger-to-nose test, or answering informational quizzes. However, only three tests are recognized and approved by the NHTSA: the Horizontal Gaze Nystagmus (HGN) Test, the Walk-and-Turn Test, and the One-Leg Stand Test. Other tests can be attacked on the basis that there has been no scientific validation that failure of the tests is indicative of intoxication.

Do I have to submit to field sobriety tests?

Submission to FST’s, like answering questions as discussed above, is voluntary, and not required by law. The officer may request them, but failure to perform them correctly, judged subjectively by the officer, may be used as additional evidence to build probable cause to support a DUI arrest. A police officer may interpret a refusal to perform FSTs as suspicious and therefore probative of intoxication, but a person who is intoxicated should not submit to field sobriety tests in hopes of passing them.

Do I have to submit to chemical tests?

Any person in Pennsylvania has the right to refuse to blood, breath, or urine testing, collectively referred to as chemical testing, in the course of a DUI investigation. However, the consequence of refusing such testing is that one’s license is suspended by PennDOT for at least one year, and in some cases eighteen months. The reason for this is that in Pennsylvania, there is an implied consent law which means that with acceptance of driving privileges, all licensed drivers operating vehicles on public roadways are deemed to have consented to chemical testing whenever there is probable cause to believe that they are driving under the influence. The suspension for refusing to take the test is assessed in addition to any suspension which accompanies a DUI conviction itself.

Should I submit to chemical tests?

There is no clear-cut “correct” answer to this commonly asked question. Steven Fairlie wrote a brief article on this topic that was published in Philadelphia Magazine, and as a result he fielded numerous questions on this topic. The threat of a license suspension as a consequence of a refusal must be weighed against the likelihood of supplying BAC evidence. For instance, a person with no prior DUI offenses and a BAC of .085 would suffer no license suspension if he took the test. If he refused the test he would be suspended for one year for the refusal and an additional year for the DUI conviction. (See DUI Penalties section). However, submitting to the test could also be what provides the state with sufficient evidence to convict a person of DUI, as opposed to walking away with no penalties at all. Therefore, the “correct” answer is highly variable and largely a matter of predicting the evidentiary outcome and weighing that against the respective likelihoods of what penalties existing evidence may have already made likely. Although there is no rule that applies across the board, the safer route is generally to submit to the test and avoid the possibility of a longer license suspension.

May I choose which chemical test I submit to?

No, unfortunately an individual has no choice as to the manner of blood, breath, or urine testing. One may request one form over another, but the request will usually not be honored. One must also be careful, as a police officer requesting a driver’s consent for chemical testing may interpret any answer other than an affirmative response as a negative one, which could constitute a refusal. Therefore, if one’s desire is to grant consent but request a preference, the affirmative response should be made clear and constant, and not undermined by the subsequent request. There are provisions for obtaining a second test privately. Please contact us at 215-997-1000 if you are interested in learning more about this option.

What is an ignition interlock device?

An ignition interlock device is a PENNDOT-approved system which is installed on the steering column of a car and serves to prevent the vehicle from being started or operated unless the operator of the vehicle provides a breath sample that yields a low enough blood alcohol level, usually less than .025%. The operator has to blow into it prior to turning on the vehicle, and while driving, the device will beep intermittently, signaling that another breath sample is required. If no breath sample is provided, or is over the required BAC, then the car will either not start, or will shut off. The ignition interlock device is called for by statute as a consequence of all second-offense DUI convictions (within the last ten years), as indicated in our DUI Penalties section.