A full 33% of teenagers think that if you’re in a state with legalized recreational marijuana, it’s legal to drive while under the influence of marijuana. That’s according to a new survey conducted by Liberty Mutual Insurance and SADD (Students Against Destructive Decisions).

Last spring, 2,800 teenagers were surveyed on their knowledge of weed and driving. 68% of teenagers said they believe driving under the influence of cannabis is dangerous.

A funny thing about this study is how misleading it is. A report put out by Liberty Mutual Insurance is headlined, “One-Third of Teens Think Driving Under The Influence of Marijuana is Legal.”

But, interestingly, the body of the report shows that adults’ beliefs about cannabis and driving are not that different from their kids. A poll of 1,000 parents showed that 27% believe driving while high is legal and 76% thought it was dangerous.

Liberty Mutual concludes from the study that “teens are receiving mixed messages about the dangers of marijuana use and driving, potentially putting themselves and others at risk.”

Part of that “mixed message” problem is that weed laws are in flux right now, sometimes changing year to year. In addition, most state laws on consumption limit are vague, sometimes to the point of meaningless as there still isn’t a standard way to test for inebriation with cannabis the same way there is with alcohol.

In Alaska, California, and Oregon, for instance, the legal limit is up to officer discretion, according to a report from Instamotor. In Colorado, the legal THC limit for drivers is 5 nanograms per millileter of blood (so if you think you’re at 4 nanograms, just take it easy for awhile before you get behind the wheel).

In Washington State, it’s 5 nanograms or officer discretion. In Nevada, it’s two nanograms of cannabis or officer discretion. THC can stay in the blood for days after it’s been consumed.