There goes Mary barreling down the road with her kids flopping unrestrained in the back seat.

The sound system is blasting so loud the bass notes buzz the window of the truck she's passing on a double line, but she doesn't notice the driver yelling at her as she weaves back into the lane, forcing him to step on the brakes because she has her cell phone at her ear, yakking with her sister about whether to pick up SpongeBob or Dora paper plates for the party.

"Make sure you get the 64-pack and not the two 32-packs because you'll save 8 cents. Yes, you will. I did the math on my calculator. Wait, I'm on my iPhone. I'll send you the party spreadsheet."

Oh, and she's smoking a cigarette.

Pull that woman over and give her a citation for the cig!

The Hawai'i County Council is considering a bill that would ban smoking in any vehicle in which a kid is riding. Bill 216 was passed by the council's Human Services and Economic Development committee this week and now goes to the full council.

The bill would make it illegal to smoke in a car where any occupant is under the age of 18.

While saving kids from the effects of secondhand smoke is a lofty goal, motor vehicle laws should regulate safe driving, not healthful living. Banning smoking will open the door to all kinds of other "we're doing this for your own good" behavior bans that would eventually put all fast-food drive-throughs and car stereo stores out of business.

Besides, if you take away cigarettes from some parents, you deprive them of the one self-calming crutch they have to get them through the day. Without a Benson and Hedges Menthol, they'll be white-knuckling it down the street screaming at the kids and losing their cool.

Lighting up in the car might prevent all sorts of worse behavior.

But the most obvious problem is enforcement.

Here on O'ahu, there are flagrant lawbreakers carrying on animated cell phone conversations with one hand holding the phone, one hand gesturing as if the person they're talking to can see and no hands on the wheel.

They're everywhere, even though it's against the law. I bet you saw somebody who was exactly like that just today, right? Right.

It's hard to imagine that a no-smoking ban would be any more successful. Picture a guy weaving down the road because he's trying to hide his cigarette by ducking below the dashboard to take a drag?

Besides, on the Big Island, a car ride with cigarette smoke hardly compares to a lifetime of vog exposure, and no one has outlawed that.