Colorado was the first state in the U.S. to legalize marijuana for recreational
use, and although driving while stoned was an issue prior to Amendment
64, law enforcement saw a greater need after the law's passage to
enact legislation that would prevent people from
driving under the influence of marijuana.
Enter House Bill 1114 – a bill signed into law that makes it illegal
for drivers to have five nanograms of THC in their bloodstream. Attempts
to put a limit on marijuana in the bloodstream have failed in the past,
but experts speculate that the legalization of recreational marijuana
made a measure like this necessary.
In California, it is illegal to
drive under the influence of any drug, intoxicating liquor, or a combination of both. California
law does not specify a threshold at which point drugs in your bloodstream
is illegal (such as the 5 nanogram threshold in Colorado). Anyone caught
with a drug, such as marijuana, in their bloodstream while driving can
be arrested and charged with DUI.
Although a limit on THC concentration is a step in the right direction,
many experts still worry that this threshold is ambiguous. Unlike alcohol
in the bloodstream, marijuana concentration is not affected by a person's
body type, weight, and how many hits they took. Marijuana's varying
effects on people make it difficult to say at what concentration a driver
is considered impaired.
The problem with THC concentration limits is that there is no blood THC
level that consistently correlates with impairment, and consequently,
blood tests are unreliable at best to determine who is driving under the
One positive trait about Colorado's 5 nanogram limit is that it is
not a per se law. Per se laws presume someone's guilt based on chemical
(breath, blood, or urine) test evidence. Anyone arrested for marijuana
DUI in Colorado, for example, is not presumed to be guilty and has the
right to contest the accusation.
California's cannabis laws are effect-based, which means that rather
than presuming guilt – and unlike Colorado's permissive inference
laws, a DUI charge can only be substantiated if evidence shows that marijuana
was recently ingested. In many states, drivers can be charged with drugged
driving weeks after they ingested marijuana because THC stays in the bloodstream
for so long.
The White House has recommended that all states pass zero tolerance, per
se marijuana laws. If every state were to take that suggestion, any trace
of cannabis would constitute a DUI charge, and all those arrested would
be presumed guilty. Colorado seems to be moving in the right direction
with their marijuana laws, because not all marijuana use has the same effect.