On Nov. 8, California residents chose to make the recreational use of marijuana legal in the state by voting in favor of Proposition 64. While news of the vote was likely welcomed by many Californians, the state's law enforcement agencies may have been less than happy. This is because there is currently no reliable way to determine whether a motorist is impaired by marijuana.
Establishing that a driver is operating a vehicle while under the influence of alcohol is relatively straightforward for police, and the effectiveness of both field sobriety and roadside breath testing have been borne out by exhaustive scientific research. However, marijuana is not processed by the human body in the same way that alcohol is, and traces of THC can be detected in a marijuana user's system weeks after the drug has been consumed and its intoxicating effects have dissipated.
This makes securing a drunk driving conviction based on THC levels alone problematic, and law enforcement has increasingly turned to field sobriety exercises to gauge marijuana impairment. However, the effectiveness of these tests have also been questioned because alcohol and marijuana affect drivers differently. Tests are being developed that could better identify marijuana-related signs of impairment, but it could be years before they are considered reliable enough to be admissible in court.
Experienced criminal defense attorneys may stay abreast of developments in toxicology and the questions surrounding field sobriety, blood and breath testing. They may also seek to have impaired driving charges dismissed when the suspicions of police officers are not backed up by credible scientific evidence. Attorneys could also question the reliability of toxicology test results when their clients suffer from certain medical conditions or the equipment used has not been properly maintained.