There's a scene in “Up in Smoke,” the 1978 stoner classic starring Cheech Marin and Tommy Chong, where the two main characters are zonked out of their minds in Cheech's car. Passing a monster joint back and forth, Cheech asks “Hey man, am I driving okay?” After a long pause, Chong responds, “I think we're parked, man.”

According to David Casarett, author of Stoned: A Doctor's Case for Medical Marijuana, that's probably for the best. Curious about the effects of Cheech and Chong's favorite plant, Casarett looks into how well people can drive while high, what marijuana tastes like when it's infused into beer, and what it does to you if you distill it down to its purest form and smoke it like crack. Turns out it makes you act kind of like you just smoked crack.

Casarett also rubs marijuana oil into his legs to see if it stops the cramps he gets on a hike, visits people who get high to alleviate pains caused by cancer, hangs out with a guy who says he's invented the ultimate smoking apparatus (called “the volcano”), and does some good old-fashioned joint-smoking to see what it does for his back pain. Along the way, he assesses which ways of getting high are most efficient, and it seems like simply rolling one up is still just as good a way as ever to indulge.

Stoned is not written by a stoner. I don't think you're likely to find Casarett's byline in High Times in the near future, and I wouldn't be surprised if he'd never even leafed through an issue. This is not a polemic railing for legalization (though he leans in favor), and he's genuinely concerned about the substance’s possible negative effects. Think it's not addictive? It certainly can be. Think it has no ill effects on brain cells? It very well might. And if you think it's okay to smoke and drive, you're way off course.

In a humorous field test, Casarett has an acquaintance get stoned and drive around an empty parking lot. Because he wasn't able to find orange cones that morning, the doctor has placed bananas around the lot to line the route he'd like his subject to drive. But before they can start the test, they have to wait a little while – getting into the car, the red-eyed driver can't remember what to do with his feet. Once he's finally feeling up to the task, he squishes a gorilla's buffet worth of bananas.

That's pretty funny. It's not “Up in Smoke”funny, but it's good. (By the way, I've been out of Cheech and Chong's core demographic for a decade, but I just watched that movie, and it's terrific.) Casarett's book elicits a fair number of chuckles, and with its digestible amount of research, it makes a sober case for getting high.