Holiday parties, reunions with old friends, and family celebrations are all common during the holiday season spanning Thanksgiving through the new year.Unfortunately, those gatherings can lead to a spike in DUI arrests and accidents, as some people choose to drive themselves home after drinking.
While DUI roadblocks, or "sobriety checkpoints" are common this time of year, law enforcement in general cannot stop a driver without probable cause. Typically,probable cause for a traffic stop includes traffic violations, such as speeding, running a stop sign, or blowing through a stop light. However, thereare other indicators and driving behaviors which can give a law officer probable cause to make a traffic stop and to suspect DUI.
The U.S. Department of Transportation, through the National Highway Transportation Safety Administration (NHTSA), provideslaw enforcement agencies with a guide that highlights potential signs of impairment and the likelihood that a driver exhibiting these signs is drivingunder the influence of alcohol or drugs.
The guide, called "The Visual Detection of DWI Motorists" lists the following four categories of indicators signalling potential DUI:
For each of these categories, the NHTSA lists a specific related behavior and the likelihood, as determined by a percentage, that the driver who exhibitsthese symptoms or a combination thereof is impaired by alcohol or drugs.
Problems Maintaining Proper Lane Position (50-75%)
Speed and Braking Problems (45-70%)
Vigilance Problems (55-65%)
Judgment Problems (35-90%)
According to the NHTSA, a combination of visual indicators increases the likelihood that the driver exhibiting them is impaired. The combination ofany two cues results in at least a 50% likelihood that the driver is under the influence; if one of those cues is weaving, the probability is increasedto at least 65%.
Of course, the search for probable cause to suspect DUI does not end when the driver is pulled over, but continues through the interaction during thetraffic stop. The NHTSA also provides a list of "Post Stop Cues" which give a probability of at least 85% that the driver is impaired by drugsor alcohol:
The NHTSA itself says that that probability of finding an impaired driver through random traffic stops is only 3%--a statistic that seems to be supportedby the number of DUI arrests made at a sobriety checkpoint compared to the number of outstanding warrant arrests.
Of course, the best way to avoid a DUI arrest is not to try to avoid these driving behaviors (many of which are also indicative of distracted drivingrather than impaired driving), but to avoid driving after drinking. During this holiday season, we encourage you to drink responsibly and to alwaysfind a sober ride.
