California Highway Patrol and local agency officers continually undergo training to assist in identifying drunk drivers.  A significant aspect of the training is to ensure there is legal justification for the stop.  If not, an experienced Fullerton DUI lawyer may have grounds to file a motion to exclude some of the evidence in the case.  If a traffic infraction or a vehicle equipment failure is the reason for the stop, law enforcement is generally speaking on more solid grounds, but where suspicion of DUI is the sole reason for the detention, the police must demonstrate a reasonable basis for that belief.

DUI Detection Guide

Under National Highway Traffic Safety Administration sponsored research, a study concluded that there is a correlation between certain identifiable driving behaviors and the likelihood the driver is impaired by the consumption of alcohol.  The following table lists 19 observations police may make, followed by the probability, based on 100 such incidents, that the driver of the vehicle in question has a BAC of 0.10 percent or greater.  Therefore, for instance, 60 out of 100 drivers observed weaving are over the legal limit, according to this guide.  Additionally, if more than one behavior is noted, the probability is increased by adding 10 to the higher number.  As an example, if a driver is observed weaving, swerving and following too closely, the probability of a 0.10 BAC is determined to be 70 out of 100 chances.

Practical Considerations

This DUI detection guide is simply another tool of many law enforcement employs, but the observations alone are insufficient to convict a driver of DUI.  For example, even if the probability that a driver is impaired is 60 out of 100 according to the guide, that obviously means that 40 are not.  Additionally, there can be other demonstrable reasons for the manner of driving observed that has nothing to do with alcohol.  And while law enforcement would have you believe they are trained to be and act objectively, an Orange County DUI lawyer can explain that many of these evaluations are in fact quite subjective.