How impaired driving laws could affect marijuana users

Ohio is taking baby steps on the way to decriminalizing marijuana. In 2012, penalties were eased for the possession of most marijuana paraphernalia. Possession of such materials had previously been a fourth degree misdemeanor, which carried a possible sentence of 30 days in jail.

The revised law, which went into effect in September 2012, changed possession of paraphernalia to a minor misdemeanor. Possession of less than 100 grams of marijuana is the same type of offense. A minor misdemeanor is comparable to a traffic ticket, carrying a hefty fine.

Meanwhile, around the country, bigger changes have been taking place. Colorado and Washington decided in the 2012 elections to legalize the use and possession of marijuana, even for recreational purposes. As marijuana loses its stigma, the fact remains that it is an intoxicant, and states must continue to deal with drivers who are impaired by marijuana, along with other intoxicants like alcohol.

Driving while stoned

Quick, reliable tests can determine blood alcohol levels, and states have adopted fairly uniform standards for defining drunk driving. However, by no means are there generally accepted tests for determining the level of drugs in a driver's system, nor is there a recognized threshold for drug-impaired driving.

In the case of marijuana, it is possible to test for the presence of THC, the intoxicating chemical component of marijuana. One of the states that legalized marijuana use, Washington, defines marijuana intoxication at 5.0 nanograms of THC per milliliter. This level of THC is believed to have approximately the same effect on driving as a 0.08 blood alcohol level, the standard legal limit for drunk driving.

Fewer than 20 other states have legally defined marijuana intoxication in terms of THC levels. About a dozen have a zero-tolerance law, so that a driver with a positive test for THC is considered impaired, no matter what his or her THC level. Pennsylvania and Nevada have included THC levels in their laws governing motorists. Ohio uses a 2.0 nanogram level as its standard for defining impaired driving.

The problems with testing

Testing for THC in a driver's system is problematic for a number of reasons. No one test has been adopted, but generally blood must be drawn, requiring a medical professional. THC breaks down rapidly in the bloodstream, so tests that measure THC won't reliably show a driver's level of impairment unless the test is administered promptly after a driver has consumed marijuana.

Some workplaces use a test that can detect a metabolic product of THC, which can indicate that a worker used marijuana up to several weeks before testing. Such a test is clearly not practical for measuring driver impairment.

The National Highway Traffic Safety Administration has determined that THC is at its peak level while a user is smoking marijuana, and blood concentrations drop to less than 5.0 nanograms per milliliter within three hours after smoking.

Looking ahead

In Ohio, some activists want to see medical marijuana use legalized, and some go so far as to advocate legalization across the board, as in Colorado and Washington. As more states see a need for legislating THC intoxication levels, there may be a move toward adopting a realistic standard nationwide.

Many toxicologists believe that 2.0 nanograms is too low a level for defining marijuana intoxication, and 5.0 is a more accurate level. If so, Ohio's standard could result in people being convicted for driving while under the influence of marijuana when they did not have enough THC in their systems to impair their driving.

While the laws are in flux across the nation, it is important to preserve individual rights for those who are prosecuted for drugged driving. Anyone who is arrested and charged with driving under the influence of marijuana needs a skilled advocate and should consult an experienced criminal defense attorney.