Banning mobile phones in cars saves lives. No it doesn't. Yes it does. No it doesn't.

Restrict cellphone use in cars and accident rates go down, right? Not necessarily. The results are mixed. Some studies show a correlation between using a phone while driving and a higher incidence of accidents. Now comes a new study on California drivers that shows virtually no meaningful change in accident rates before and after a cellphone ban took place. Unless this study is refuted, the best safety advocates can say is that cellphone bans may improve road safety.

Can you poke a hole in the methodology?

Enter Rand Corp., the University of Colorado, and a statistics expert from Colorado School of Mines. They teamed up to study California’s traffic accident database before and after the ban. The research was modeled to account for multiple factors, including weather, gasoline prices, number of drivers on the highway and traffic density, holidays, total miles driven, and ever-safer cars. If, for instance, it was rainier and gas prices rose in the second half of 2008, there’d be fewer drivers and fewer miles driven and that alone would reduce accident rates. With those factors accounted for, the report concluded there was no meaningful change in accident rates.

Note that the Berkeley study was for a longer period -- two years before and after July 2008 -- and of traffic fatalities not accidents. But you need a longer study period if it only covers fatalities. In California, 2008 traffic injuries outnumbered fatalities 70:1 -- 241,873 traffic injuries, 3,401 deaths -- according to the state’s 2008 traffic records(Opens in a new window). So the state’s criticism of the Rand-Colorado study -- that it encompasses too short a time frame -- could be leveled at the UC Berkeley study in terms of not as many data points.

Reasons for no change in accident rates

• Drivers who continued talking on the phone may have been distracted drivers already.
• Drivers may have ignored the law. Anybody who lives in a hands-free-only cellphone state sees plenty of drivers ignoring the ban.
• Other studies miscalculated (overestimated) the risks of being distracted.

Daniel Kaffine, an associate professor at Colorado and an author of the study, told PSMag(Opens in a new window), “It’s possible that people who continued to use their cell phones were people who were more inclined to get into accidents anyway ... The other side of the coin is just that maybe it’s the case that cell phones aren’t as risky as some of these previous studies have suggested.” Kaffine says the research team was “agnostic” about the causes.

A 2007 Pepperdine University study by James Prieger and Robert Hahn carried the provocative title, “Are Drivers Who Use Cell Phones Inherently Less Safe?”(Opens in a new window) and concluded that "drivers who use mobile phones while driving may be more likely to get into accidents than drivers who do not, even when they are not using the phone."

In-car communications options may be limited even more

Already 14 states, along with DC, Puerto Rico, Guam and Virgin Islands, have a ban(Opens in a new window) on use of hand-held cellphones in cars. Even more restrict texting. Many place limits on device use by young drivers.

There has been talk -- so far, only talk -- that use of any mobile device should be disallowed in the car, for instance by jamming the device’s radio frequency. The argument is that you can’t trust the driver to not pick up the phone to check a text; safety is a small price to pay for no one in the car being able to use a portable device. Problem is, most drivers rightly calculate their odds of being in an accident are low. The average driver is in an accident every 15-20 years. The fatality rate currently stands at one per million miles driven, or once every 700 years.

Self-censorship by device makers limits what you can do in the car. Apple CarPlay and Android Auto, which replicate smartphone apps onto the car’s LCD display, lock out any app that isn’t approved. If you or your passenger want to check the weather and the car is paired to the device, it’s locked out. The only way to gain full access to, say, an unsupported navigation app, is to unpair your phone. It’s possible some drivers will do just that and lose whatever safety benefits accrue from being hands-free.

Academics always close their papers by saying “more research is indicated” -- meaning “fund us for more studies.” Here there’s need for more and deeper research that looks into whether drivers who ignore cellphone or texting bans are already more accident-prone. Conversely, there may be an uber-class of drivers who deal well with multiple inputs, just as TV announcers can read the news while listening to the producer’s directions in his or her earpiece.

It wouldn’t hurt to learn what else is distracting. Right now, technology is the villain. Texting and cellphone use are both described as being “as bad as driving drunk,” although there’s a big difference between the tipsy-and-legally-drunk threshold of 0.08% BAC where you shouldn’t be driving and 0.16% BAC where you’re closer to unconscious than sober. Historically, the two causes of distracted driving accidents have been a bee in the car, reduced now with air conditioning and closed windows; and dropping a lit cigarette or lighter in your lap, reduced with the decline in smoking. Tuning the car radio is considered to be a distraction, but so too are pedestrians in short skirts and getting close enough to read the bumper sticker on the car ahead. Some research suggests listening to phone calls hands-free, or to voicemail, is distracting.

Another study worth doing: Seeing how much forward collision warning, lane departure warning, and drowsy driver sensors cut the risk of accidents. Technology may save us from our own lapses in judgment.