Most DUIs (driving under the influence) and DWIs (driving while intoxicated) stem from the use of alcohol or illegal drugs. However the use of legal drugs -- prescriptions or over the counter medicine -- can can also lead to impaired driving and possibly arrest.
Consider this scenario: A professional mother of two is getting ready for work one morning. The night before, she took her usual antidepressant medication as well as a pill for hay fever allergies. Both pills cause drowsiness. That morning, she has a severe headache, so she pops a couple of prescription pills, which also cause drowsiness -- and contain a warning that one should not operate a vehicle or other machinery after taking them. She kisses her children goodbye, gets on the road, fails to notice another car at a four-way stop, and plows right into it.
A police officer arrives, and the woman apologizes profusely, saying, "I've never had any driving troubles -- it must be all this medication I'm on."
Unfortunately for her, the woman has essentially now admitted to a DUI or DWI, depending on her state.
The typical elements of a DUI or DWI offense are:
Although the language above represents a melding of the laws of the 50 U.S. states, no state punishes only those people whose driving impairment resulted specifically from alcohol or illegal drugs alone. Someone impaired by legal drugs can ordinarily be found guilty and punished for driving while under the influence in the same way as any drunk driver.
Massachusetts law, for example, actually spells out some of the possible impairment-causing drugs, mentioning "narcotic drugs, depressants or stimulant substances." (M.G.L.A. 90 § 24.) And California law specifically notes that "The fact that any person charged with [a DUI] . . . is, or has been entitled to use, the drug under the laws of this state shall not constitute a defense . . . ." (VC 23630.) California further singles out drug use by making it a crime for anyone addicted to a drug -- other than methadone for treating heroin addiction -- to drive a vehicle. (VC 23152(c).) And as we all know, both legal and illegal drugs can lead to addiction and impairment.
Unfortunately, the standards for how much of a drug can be in someones system without causing impairment are not yet set. In other words, theres no comparable standard to the 0.08% maximum set for blood alcohol (BAC) levels.
This issue will probably receive increased attention in coming years, however, because the National Highway Traffic Safety Administration has become concerned about the impacts of drug use on driving. In a July 2009 report, the NHTSA found that while drunk driving has decreased markedly in recent years, approximately 16% of nighttime drivers have some sort of potentially impairing drug in their system. The NHTSAs list of potentially impairing drugs tracked in this study included not only illegal drugs, but prescription and over-the-counter products such as stimulants, sedatives, antidepressants, and narcotic analgesics.
The NHTSA report says, "Determining which drugs and dosage levels impair driving related skills is a large undertaking given the number of potentially impairing drugs. NHTSA has convened an expert panel to begin identifying methods for assessing impairment . . . ."
In the meantime, you can expect a combination of the facts concerning the driver's behavior -- such as weaving, performing reckless maneuvers, failing to observe street signs, or exhibiting slow reactions to road hazards or events -- combined with evidence that the person had a legal drug in their system that has known, potentially impairing side effects will continue to lead to DUI or DWI convictions.
For more information on misdemeanor DUI and DWI charges, see Nolo's article Dealing with a DUI or DWI Charge. If you need an attorney, see Nolo's Lawyer Directory, which provides in-depth profiles and information to help you select the right attorney.