Contrary to public belief, it is not illegal to drink and drive. It is illegal to drive under the influence of alcohol, drive while intoxicated, drive while intoxicated, or drive in a condition that your state says is illegal. Believe it or not, police officers are trained to recognize when a driver is in this condition. Now before we go too far, I want to point out that I am a DUI attorney in Maryland, Virginia, and DC. But this is not legal advice. It is merely informational and is not specific to any situation. If you need legal advice or professional assistance for your own situation, you should contact an attorney licensed in your state.

For the sake of consistency, I will use the abbreviation “DWI” throughout this article, but it could easily substitute for “DUI,” “OUI,” or “OWI.” Police officers are trained to divide DWI detection into three phases: moving vehicle, personal contact, and pre-arrest review.

1) Phase 1: Vehicle in motion.

In phase 1, the police officer is trying to answer the question of whether to stop the vehicle. It begins with the initial observation of the vehicle and the way it is driven.

2) Phase 2: Personal contact.

In phase 2, the police officer is trying to answer the question of whether to ask the driver to get out of the vehicle. It begins with initial contact with the driver and observations from the police officer. During the personal contact phase, the officer has the opportunity to observe and speak with the driver.

3) Phase 3: Pre-arrest evaluation.

In phase 3, the police officer is trying to answer the question of whether there is probable cause to arrest the driver for DWI. Most of the pre-arrest evaluation is field sobriety tests. The National Highway Traffic Safety Administration, a division of the Department of Transportation, recognizes three standardized field sobriety tests: the horizontal gaze nystagmus test, the walk-and-turn test, and the one-leg stand test. Additionally, officers often administer a preliminary breath test or other non-standardized field sobriety tests.

Throughout the three phases, the police officer is trained to look for certain clues that increase the likelihood that the driver will be affected. The officer is also trained to include each clue in a police report. Sometimes all three phases are not present in a particular DWI stop. For example, if there is a collision involved or the stop took place at a barricade, one or more of the phases may be absent.

Of course, the next logical question is what to do when you have this information. That’s what your DUI lawyer is for: use this knowledge and any other evidence to put together your best defense.