A bill before the governor of Illinois would change the state of DUI law for marijuana users, making it legal for individuals to drive with as much as 15 nanograms of THC per milliliter of blood in their system. THC is the primary psychoactive chemical in marijuana. The governor has not made public whether he intends to sign the bill into law. Critics have pointed out that the new limit would be the highest in the United States. Colorado and Washington, which have legalized marijuana for recreational use, each use a limit of 5 nanograms.
If the bill becomes law, the 15-nanogram limit will replace the state's zero tolerance policy, pursuant to which a driver may be charged with impaired driving if he or she tests positive for THC or its metabolites in any amount. It's problematic because THC may remain in a person's system for weeks or months, long after the effects of marijuana use have dissipated.
The National Organization for the Reform of Marijuana Laws advocated an actual impairment standard, whereby authorities would be required to demonstrate that the driver was impaired, via field sobriety tests, for example, rather than merely establishing the presence of THC in the driver's system. The standard set forth in the bill is the result of compromise among legislators and other interested parties.
House Bill 218 also would decriminalize possession of marijuana for amounts up to 15 grams. Individuals faced with a DUI charge related to marijuana, alcohol or other substances may be fined or jailed if convicted. An attorney with experience in criminal defense may be able to help by interviewing law enforcement officers or other witnesses to search for weaknesses in the prosecution's case. An alternative may be to negotiate a plea agreement with prosecutors that could mitigate the penalties.