Not all DUI arrests stem from someone swerving wildly off the road or crashing into a tree in the purview of a police officer. Law enforcement are, however, trained to look for certain signs that signal drunk driving. If you are pulled over and more of these signs exist, an officer may have probable cause to believe you were driving under the influence and could subject you to a breathalyzer or other chemical/field sobriety test. If you have alcohol, any drug, or any drug metabolite in your body that raises your blood alcohol content to a 0.08 or higher when you are in physical control of a vehicle, then you could be arrested for a DUI.
What behaviors do law enforcement typically look for to determine if you are driving under the influence? Police officers need probable cause to believe that you committed a crime. Probable cause can be formed for a variety of reasons, including an accident or injury. Basically probable cause is an officer’s reasonable belief based on articulated facts that a crime is being committed.1 The behaviors that law enforcement look for typically include making wide turns, swerving and over-correcting, driving under the speed limit, erratic driving actions, weaving or straddling the center line, or abrupt turns.2 If you are pulled over for these reasons, it does not necessarily mean the officer suspects you for drunk driving. However, these are behaviors that are common in DUI cases. The National Highway Traffic Safety Administration (NHTSA) says that one or more of these behaviors does show a probability of drunk driving.3
However, you can also be pulled over for any reason, such as a traffic violation. These are called pretext stops. Observations continue once you have been pulled over. According to the NHTSA, there are various ways to estimate probability of drunk driving just from observation. In fact, post-stop cues are the ones where the NHTSA recommends that the likelihood of drunk driving increases to 85% or more.4 If two or more visual cues are combined, then law enforcement can assume that the probability of drunk driving is over 50%.5 The NHTSA lists the following6:
|Probability of 3%||Usage of random traffic enforcement at night|
|Probability at 35%-90%||Judgment Problems
Following too closely, improper or unsafe lane changes, illegal or improper turns, driving on something other than a designated roadway, stopping inappropriately in response to an officer, inappropriate or unusual behavior (such as throwing or arguing), appearing to be impaired
|Probability at 45%-70%||Speed and Braking Problems
Stopping problems, accelerating or decelerating for no apparent reason, varying speed, slow speed (10 or more miles per hour under the speed limit)
|Probability at 50%-75%||Problems Maintaining Proper Lane Position
Weaving and weaving across lane lines, straddling a lane line, swerving, turning with a wide radius, drifting, almost striking a vehicle or object
|Probability at 55%-65%||Vigilance Problems
Driving in opposing lanes or wrong way on a one-way street, slow response to traffic signals, slow or failure to respond to officer’s signals, stopping in a lane for no apparent reason, driving without headlights at night, failure to signal or signal inconsistent with action
|Probability greater than 85%||Post Stop Cues
Difficulty with motor vehicle controls, difficulty exiting the vehicle, fumbling with driver’s license or registration, repeating questions or comments, swaying or balance problems, leaning on the vehicle or other object, slurred speech, slow to respond to officer or officer must repeat, providing incorrect information and changing answers, odor of alcoholic beverage from the driver
As you can see, some of these suggestions are broad. Law enforcement are given a probability range of 35-90% likelihood that you are drunk if you “appear to be impaired” because of judgment problems. Appearing to be impaired does have several visual cues, such as eye fixation, tightly gripping the steering wheel, face close to the windshield, driver’s head protruding from the vehicle, gesturing erratically or obscenely, or slouching in the seat.7 It can be difficult to determine whether someone is drunk based on certain behaviors because there is a lot of generalization. However, these are the general directions law enforcement are given based on NHTSA research and they take time for law enforcement to practice.
Contact the 24 hour Phoenix dui attorneys at Ariano & Reppucci to get your questions immediately answered.
1 See Probable Cause, LEGAL-DICTIONARY.THEFREEDICTIONARY.COM, http://legal-dictionary.thefreedictionary.com/probable+cause (last visited Jan. 21, 2015).
2 Candace Kallen, Police Look For Certain Things In DUI Arrests, MYAZLAWYERS.COM, http://myazlawyers.com/dui/law-enforcement-notice-looking-drunk-drivers/ (last visited Jan. 21, 2015).
3 The Visual Detection of DWI Motorists, NHTSA.GOV 5-6, http://www.nhtsa.gov/staticfiles/nti/pdf/808677.pdf (last visited Jan. 21, 2015).
7 Drunk Driving (DUI/DWI), JUSTIA.COM, https://www.justia.com/criminal/drunk-driving-dui-dwi/docs/vehicle-in-motion.html (last visited Jan. 21, 2015).