There are certain behaviors that officers look for when they study people driving that give clues about whether or not the driver is impaired. Driving with your face too close to the windshield, staring forward or putting your head out the window, will raise concern with police. Gripping the steering wheel very tightly, making obscene gestures or yelling at people will do the same. Even more obvious behaviors include chasing another car, cutting people off, weaving in and out of traffic, or hitting or almost hitting other cars or property. If you violate other traffic rules, such as running stops signs or red lights or driving without your headlights on, you are almost guaranteed to draw unwanted attention to yourself.  Also, if you become reckless with your driving by driving in the wrong lane, going in the wrong direction on a one-way road or driving completely off the road, you will virtually guarantee a traffic stop and most likely an arrest.

Alcohol impairs many of the judgments and reactions you need for driving. Police officers use these visible clues to determine your impairment. Police officers may use simple tests such as making you walk in a straight line or touch the tip of your nose with the tip of your finger, but those tests are just indicators of your coordination, and coordination is greatly affected by consumption of alcohol. These tests are called field sobriety tests.

Alcohol reduces your ability to stay focused, makes hand-eye coordination extremely difficult, and limits your peripheral sight.  It slows your ability to react to the things that happen while you are driving, such as traffic lights changing or quick movements from other vehicles.  Being impaired by alcohol also makes it more difficult to multitask: shifting while depressing the clutch, driving between designated lines on the road while maintaining the proper speed, or activating a signal before a turn while still managing to respond to traffic.  Actions such as these make it very easy for officers to recognize suspicious vehicles.

In 2007, the National Highway Traffic Safety Administration (NHTSA) launched a nationwide campaign to reduce drinking and driving. You have probably heard the catch-phrase: “Over the Limit: Under Arrest” wherever you happen to live. The NHTSA provided training and marketing materials to police stations across the country; officers are more educated and motivated to remove dangerous drivers from the street, and unfortunately, a lot of social drinkers are getting caught up in the political pressure.

Stay tuned for Part 3: Dos and Dont's of a Traffic Stop

This post contains excerpts from The DWI Book, the definitive guide to protecting your rights in the face of New Hampshire's tough DWI/DUI laws.