Under California law, it is illegal to drive under the influence of marijuana. If you're found driving under the influence of marijuana, then you can be arrested and charged with DUI. The presence of marijuana in your system is typically detected using a chemical test, to detect traces of the pot in your blood.
However, in the future, officers may use a breathalyzer which is believed to be much more accurate and reliable in detecting the amount of marijuana in the system.
A team of researchers is currently working on such a breathalyzer, and as part of their study, they recently took blood samples from people who constantly used marijuana, as well as occasional users of marijuana after smoking THC joints. Among the persons who smoked marijuana chronically, all of the blood samples tested positive for the drug after one hour. However, after four hours, only one of the samples collected remained positive.
Among the persons who smoked marijuana occasionally, roughly 91% of the samples were positive after about one hour. According to the researchers, the breathalyzer may be a better option, but only between half an hour to two hours after the intake.
The researchers believe that a breathalyzer test would be a much better tool to detect the amount of marijuana in the system, than blood tests. Chemical blood tests may be unreliable, because it is hard to tell exactly when the marijuana was inhaled. For example, a person may continue to have marijuana in his bloodstream for between 2 to 7 days after smoking a joint. Several days later, he may still continue to show traces of marijuana in his system in a THC test. A breathalyzer test would be much more accurate.