Below is a description of the gathering of evidence by the police that is often used later in a trial:
When the police suspect someone of driving drunk, they first make a note as to whether the driver is committing a traffic violation(s) (speeding, failure to put on a turn signal, etc.) or because of weaving in a lane. Once the police note such driving behavior, they are permitted to pull over the driver. For DUIs originating from an accident, the police are permitted to arrive on the scene and question the persons involved in the accident (called the care taker rule).
As they approach the driver, they are ready to start a battery of tests to gather evidence for trial. The first set of tests is called the pre-exit test and refers to obtaining evidence even before an individual gets out of the vehicle. and normally starts with determining whether the driver has an odor of alcohol and whether it is a strong or weak odor. Second, they make a visual and audio observation of the driver to note whether the driver has slurred language or glassy, blood shot eyes.
Next, the officer asks whether the driver has been drinking and makes note of the answer. The final pre-exit test is to ask for license and registration and is meant to see if the driver is able to understand the instruction and is able to obtain the requested documents without fumbling for them and providing the correct ones.
The next test is called the post-exit test and involves taking notes of how the driver exits the vehicle (leaning on the door for support or difficulty with exiting).
Once the driver is outside the vehicle, the officer notes whether the driver is able to keep their balance or they are instead swaying.
Next the officer may start the pre-standardized field sobriety tests. These tests include asking an individual to recite the alphabet (backwards or to start from a certain letter and stop at another specific letter), counting of numbers, drawing, touching one’s nose to name a few. The important thing to do know about these tests is that there is no scientific backing proving that poor performance reflects impairment and the law firm argues this point in court and/or has the prosecution or the officer admit to this fact.
The next test the officer performs is the standardized field sobriety tests (SFSTs). The important thing to mention about these tests, is that unlike the pre-SFST test above, the SFST do have some scientific backing and so the strategy for these tests is to minimize any weaknesses (such as if someone put their foot down during the one foot stand test, or decided to not to one of them). The SFST consist of three tests: Walk and Turn, Horizontal Gaze Nystagmus, and the one foot stand.
The next test is for the officer to offer a Preliminary Breath Test (PBT). An individual is not required to take the PBT and any result from the PBT can not be used at trial (however it can be introduced in a pre-trial motion). The main purpose the officer is using the PBT result is to determine if the PBT shows a .08 and thus a presumption of impairement and which will allow him to arrest the individual. The officer is not required to offer a PBT and failure to do so is not a defense for trial purposes but may be a defense to a pre-trial motion.
Once at the station, the officer prepares the individual to take the station’s breathylizer test (in Virginia, the 2 machines used are the Intoxication 5000 Breathalyzer and the EC/IR II) by reading the implied consent law and by performing a 20 minute observation to make sure that the individual is not chewing, eating, burping or vomiting or other physical behavior that would result in there being an increase in mouth alcohol.
The results of this Breathalyzer test are admissible in court and a major priority in defending clients who do take the Breathalyzer test is to argue that due to technical/scientific issues with the Breathalyzer machine that the results obtained should be excluded so to avoid the Commonwealth from relying on the Breathalyzer test to obtain a presumption of impairment.