Reasonable suspicion and Probable Cause
It may come as a surprise to most people that police officers are not required to have probable cause to pull someone over. All that is necessary is that the officer has a reasonable suspicion that a crime has been or is about to be committed. So, it is easy to conclude that police officers can, and do, pull people over anytime they are suspicious and just want to check it out.
But, most police officers do pull drivers over based on probable cause. Probable cause basically means that there are sufficient facts and circumstances that have lead the officer to believe that a crime has been or is being committed. The more basic examples of probable cause are simple traffic violations such as speeding, running a red light, failing to signal a turn or failing to completely stop at a stop sign. Although not serious in nature, any one of these traffic violations is all an officer needs to provide him with probable cause.
Another obvious situation, which would give an officer probable cause, is a person driving recklessly. This type of behavior gives an officer probable cause to believe that the person behind the wheel may be intoxicated.
Once pulled over, the individual may be asked to exit the vehicle. The officer does not have to believe, at this point, that the person is DUI. If the stop was based upon reasonable suspicion, the officer may detain the driver long enough to confirm whether or not his suspicions were true. At this point, the officer may conduct a more thorough investigation to determine whether or not the individual was driving under the influence.
A more thorough investigation usually involves the officer asking the driving directly whether or not they have been drinking. If the individual answers yes, the officer then has probable cause to request the driver to perform a field sobriety test. If however the driving answers that they have not been drinking, the offer will look for signs of intoxication such as the smell of alcohol, bloodshot or watery eyes, slurred speech or anything else that leads the officer to belief the driver may be intoxicated. The officer may then base probable cause on what he observes and request the driver to perform a field sobriety test.
What most people do not know is that no one is obligated by law to perform a field sobriety test. These tests are subjective and therefore unreliable. Police officers use these tests simply to determine whether or not the individual is intoxicated. These tests are administered the same to everyone regardless of their age, health, or physical stature and are therefore not equal. Some people perform better than others even when all are completely sober. For this reason, defense attorneys challenge field sobriety tests when they are used as probable cause for the police officer to arrest an individual.
The same applies to roadside breath tests, also known as intoxilyzers. It is not mandatory that any one perform a roadside breath test upon the request of a police officer. However, if you are pulled over and asked to perform either the field sobriety test and/or breath test and you refuse, the police officer will more than likely arrest you based on his observations and, once at the police station, you are required by law to provide either a breath or blood sample.