Nearly three years after California voters approved a cannabis legalization bill that promised, among other things, to clarify the issue of driving while high, researchers and law enforcement have few concrete answers about a potentially deadly problem.
It’s unclear, for example, if marijuana-related arrests or car crashes have increased statewide. It’s up to each county to track that data, and many still don’t distinguish between cannabis and other drugs in their arrest and accident reports.
There also aren’t yet any reliable methods for testing whether drivers were actually impaired by marijuana when they’re behind the wheel. Research in this area is hampered by federal law and left scrambling to catch up with the wave of marijuana legalization that continues to sweep the country.