By John Keilman MCT

Over the last eight years, high school students who have gotten in trouble for drugs and alcohol have told counselor Cathy Cratty the same alarming story about driving under the influence.

“It just kept coming up, left and right: ‘We know we shouldn’t drive after drinking, but it’s OK to drive after smoking pot,'” said Cratty, who works for Highland Park, Ill.-based School District 113.

According to national surveys, high school students are as likely to drive high as they are to drive drunk. But experts say many of those teens never hear a warning about taking to the road while stoned and don’t think they’re doing anything dangerous.

“They perceive themselves as being less impaired when smoking marijuana,” said Jocelyn Boudreau, a social worker at the Rosecrance adolescent treatment center in Rockford, Ill. “The overarching and clear message [to teens] has been: ‘You drink, you drive, you die.’

“There really hasn’t been that same kind of consistent message for marijuana.”

That’s largely because pot’s role in fatal crashes is far from clear. The National Highway Traffic Safety Administration, which keeps statistics on wrecks involving alcohol, does not have enough data to generate similar numbers for marijuana.

Heidi Coleman, chief of the safety administration’s impaired driving division, said many police officers likely never detect pot because they aren’t trained to read physical cues – such as pupil size, body temperature and heart rate – that suggest the drug’s presence.

“They may suspect that a driver is impaired, but if they don’t test positive for alcohol, [officers] may let them go,” she said.

Research into marijuana’s impact on driving is similarly limited, she said.

While state law treats measurable levels of pot or other drugs as evidence of DUI [similar to a blood-alcohol reading of 0.08 percent or higher], science is more nebulous.

Some studies have linked marijuana to decreased attentiveness, slower reactions, diminished motor skills and a worsened ability to estimate distance, but there is no consensus about how severe the effects are or how long they last.

The debate over what really constitutes impairment will likely play out in a Lake County, Ill., courtroom later this year when Richard Wood, 17, faces trial in the deaths of two friends who were passengers in a car he wrecked Nov. 13.

Prosecutors, who say the Mundelein teen had used pot within 24 hours of the crash, have charged him with aggravated driving under the influence of drugs and reckless homicide. Wood’s attorney, Robert Gevirtz, would not comment on his client’s alleged marijuana use but said he would prove that his client was not impaired at the time of the crash.

Tabitha Fischer, 19, has no doubt that marijuana worsened her driving when she was growing up in Belleville, even though she saw nothing wrong with it at the time.

“When I was doing it, I thought I was a better driver,” said Fischer, who recently completed a year of substance abuse treatment at Rosecrance. “As I look at it now … I’d go through stop signs, stoplights, and I’d just laugh it off. I didn’t focus on anyone else on the road, from what I can remember. It was like I was the only person there.”