How Police Determine If Someone Is Driving Under the Influence

Driving under the influence (called a DUI when charged) is something no state takes lightly. Since it poses a threat to other drivers and pedestrians on the road, police are extra vigilant in looking for signs that a driver might be drunk or impaired by a drug. Once they pull you over, an officer may use specific tests to determine if you are impaired. A positive result can lead to an arrest and other penalties. Here’s how police determine if someone should receive a DUI.

Initial Driving Observations

Obviously, to be charged with a DUI, a police officer first has to notice something is amiss with a person’s driving ability. Someone who is driving recklessly, going too slow or too fast, weaving in and out of traffic sporadically, or showing any other strange driving techniques may signal to an officer that the driver is impaired. This initial observation is what will cause them to pull you over.

In-Person Observations

Once they can speak to you directly, an officer will make other observations to further indicate if you are drunk or have drugs in your system. Slurred words, bloodshot or glassy eyes, stumbling, drowsiness, intense energy, disorientation, or the smell of alcohol or marijuana are all things an officer is trying to identify.

Field Sobriety Tests

A field sobriety test can be a series of actions and tasks an officer asks a driver to perform. These tests are meant to measure the driver’s mental and physical state as they might relate to impairment. They usually include walking and turning (to see physical ability and the ability to follow directions), horizontal gaze nystagmus, and standing on one leg. Failing these tests could indicate to an officer that you are impaired.

Breathalyzers and Blood Tests

On site, an officer may have you blow into a breathalyzer to measure your blood alcohol concentration levels. Anything over .08% is illegal to be driving with. At the station, they may run a blood test to see if any drugs were in your system at the time.

The problem with sobriety tests, breathalyzers, and blood tests is that the results are not always accurate. Anyone can fail a sobriety field test if they are nervous or have poor balance even when sober. Breathalyzers frequently report wrong results, and even blood tests can turn out incorrect. Talking to a lawyer, like a DUI lawyer from Hallinan Law Firm, is sometimes the right option when facing DUI charges.