Cell phones are dangerous to use in the car, right? Right. Studies show that you're more distracted and have slower response times when on the phone in a car. About 1500 people die per year because they were on a cell phone.
Cell phones are less dangerous when they are hands free, right? No.Studies show they are equally distracting. This is because the impairment is due to your attention being tied up, not your hands.
Isn't talking on the cell phone in the car is just as dangerous as talking to a passenger in the car? No, because the passenger in the car is in your context. You will notice that when traffic gets crazy,or someone runs in front of the car, your conversation partner, if she's in the car, will stop talking. She knows you need the attention to drive. On the other hand, someone on a cell phone demands answers from you as though you were sitting at home. They don't stop talking no matter what happens in the car.
If cell phones are dangerous to use in the car, then this practice should be outlawed, right? Not necessarily. There is a gain in productivity by being able to talk on the phone. To give a simple example, there have been many occasions where I got directions to a place, while I was driving there, on the cell phone. If I had to pull over every time I wanted to talk, I would have wasted several minutes.
Can you imagine if everyone on the highway tried to pull over to the shoulder, stop, and turn their flashers on every time their celly rang? Fully eight percent of people driving are yakking on the cellphone. 60% of minutes sold are used in cars. The shoulders would be full, and we might even have more accidents with all the people rushing to pull over.
We spend a lot of time in the car, and lot of time on the phone. Most of the time, driving doesn't require all that much attention, but we save a lot of time by talking on the phone in the car. I saw a talk by an expert in this field, John D. Lee, and he said that the analyses done show that with the increase in accidents and the increase of productivity, the overall good ends up being about the same whether or not you talk on the phone in the car (Josh Cohen at the Harvard Center for Public Policy apparently showed this, but I have not tracked down the reference yet).
Interestingly, the debates regarding whether cell phones should be legal to use in the car mirror those debates regarding whether or not radios should be legal in cars. Turns out that listening to the radio is almost as dangerous as talking on the cell phone. About a thousand people die per year because they were listening to the radio in the car. If you're listening to a fascinating radio program, just like a conversation partner on the cell phone, the voice won't shut up just because you're hydroplaning. You can't even say "hold on" and get them to stop talking. You have to turn the radio off and miss stuff.
It's not all gloom and doom-- cell phones and radios also prevent some accidents by keeping people awake. It's also been shown that drivers drive more slowly and stay more distant from other cars when on cellphones, probably due to risk compensation.
Pictured is a piece of graffiti from my neighborhood, centretown Ottawa. This artist writes "no air" all over the place.