As the use of marijuana has become more widespread and legalized, a great deal of attention has been focused on its effects on drivers and vehicle accidents. Arizona DUI laws do not in general differentiate between marijuana impairment and being under the influence of alcohol. However, there is still a great deal of argument as to whether or not drivers are truly impaired.
There is presently a significant lack of proven science regarding the influence of marijuana on drivers. While it may be obvious that marijuana use impairs driving ability, the exact levels of influence and impairment have not been defined. Unlike alcohol, which tends to have more predictable effects on behavior and perception, scientists have argued that marijuana is much more variable. Some people will be significantly impaired by only a small amount, while others could consume much greater amounts without being affected.
There is also a general lack of ability to easily test for marijuana use in drivers. This has led to a technological race among companies to develop device similar to a breathalyzer that could help police determine the concentration of marijuana in a person's system. Most of these devices focus on THC, the primary chemical compound in marijuana associated with its psychoactive effects. The logic follows that if people test for a significant concentration of THC, then they will be impaired. This is the same line of thinking as blood alcohol level for alcohol intoxication. Unlike blood alcohol limits, however, most of the current THC limits are arbitrary and unproven.
The uncertain status of scientific evidence means that handling DUI charges related to marijuana could be both complex and hopeful. Uncertainty in the law may create situations for criminal defense attorneys to create strategies for successfully combating the allegations.