Law enforcement agencies can easily detect whether someone has a blood alcohol content of 0.08% or above with the use of a breathalyzer machine.
However, whether someone is “under the influence” of alcohol pursuant to Penal Code 23152(b) is subjectively determined by law enforcement with the use of field sobriety tests. Officers use the same standard to determine if someone is under the influence of marijuana.
To determine whether someone is under the influence for purposes of a DUI of marijuana, officers will perform many of the same field sobriety tests that they would when investigating a DUI of alcohol. The theory is that the field sobriety tests will still determine whether the marijuana is affecting the person’s ability to operate a vehicle safely. While officers may be able to subjectively determine if someone is “under the influence” of marijuana, there is no way for officers to quantify someone’s level of “stoned-ness” or the time that has passed since the person smoked.
THC is the psychoactive component of marijuana that gives the user a high and could affect the user’s ability to operate a vehicle safely. Unlike alcohol, THC from marijuana use stays in the system for weeks even though the initial high may only last a few hours.
According to Reuters, the National Institute on Drug Abuse is currently researching and developing a new machine that tests saliva to tell if a person has smoked marijuana recently. The new machines, however, will not be able to tell how high someone is. In fact, Gil Kerlikowske, current Director of the Office of National Drug Control Policy, stated, “I’ll be dead – and so will lots of other people – from old age, before we know the impairment levels.”
If the new saliva test can tell officers whether someone has smoked “recently,” what is the definition of “recent?” And how recent does the smoking need to be for someone to be considered “under the influence?” If law enforcement agencies begin using these machines, we’ll soon find out.