The US Department of Transportation will be holding its Distracted Driving Summit in Washington, D.C. this week (Sept 30–Oct 1). Among the agenda items that transportation officials, safety advocates, law enforcement authorities and academics will ponder is the question of how to reduce the risks of cell phones and driving.

So far, some states require hands-free devices, while others have outlawed mobile phone use behind the wheel altogether for some drivers. (Scroll down for a state-by-state guide to legislation.) But — and here’s an interesting twist — critics are arguing that these states have been sending mixed messages: Of those that have cell phone bans in place, more than 20 of them also offer some type of up-to-the-minute traffic and roadway updates via tools like Twitter.

Some safety experts and politicians think this is a dangerous contradiction. They believe that when states prohibit cell phone use for drivers, while simultaneously offering traffic info (that will most likely be accessed en route via mobile devices), it waters down the message. State transportation officials disagree. They say the service is intended for people to access prior to hitting the road.

Traffic Tweets aside, the biggest source of confusion for drivers may be the laws themselves. It’s not always clear what’s permissible, given that every state restricts different activities, and sometimes only for certain drivers. Even when a person knows what’s legal at home, the same activity across state lines could land that driver in hot water.

To clear up the morass of legislation, the Governor’s Highway Safety Association (GHSA) posted a state-by-state chart that breaks down the laws to date (a snapshot of which is below).

Here are a few other tidbits from GHSA:

• Handheld Cell Phone Bans for All Drivers: California, Connecticut, New Jersey, New York, Oregon and Washington. (The District of Columbia and the Virgin Islands prohibit all drivers from talking on handheld phones while driving.)

Except for Washington state, these are all primary enforcement laws. That means a police officer can ticket a driver for using a handheld phone behind the wheel without other traffic offenses taking place.

• Do any states ban all cell phone use while driving?: Yes — and no. None have comprehensive bans for all forms of cell phone use (whether handheld or hands-free) for all drivers, but many prohibit usage for specific people.

-Novice Drivers: 21 states and the D.C. outlaw all cell use by novice drivers.

-School Bus Drivers: In 17 states and the D.C., school bus drivers are banned from any cell phone use when they have passengers.

• Texting on the road: 18 states and D.C. now ban text messaging for all drivers.

-Novice Drivers: 9 states ban texting by novice drivers.

-School Bus Drivers: Only 1 state prohibits school bus drivers from texting while driving.

The chart outlining the regulations state-by-state follows. (For the full chart in a larger font, including specific information for each state, click here.)

1 Illinois bans the use of cell phones while driving in a school zone or in a highway construction zone.
2 During the 2008 legislative session, Louisiana passed 3 different cellphone laws addressing teen drivers. The governor signed all three. It is unclear whether both handheld and hands-free phone use is prohibited, or whether only handheld phone use is banned. All 3 laws prohibit text messaging.
3 Maine has passed a law making it against the law to drive while distracted in the state.
4 In Michigan, teens with probationary licenses whose cell phone usage contributes to a traffic crash or ticket may not use a cell phone while driving.
5 Dealt with as a distracted driving issue; New Hampshire enacted a comprehensive distracted driving law.
6 Texas has banned the use of hand-held phones in school crossing zones.
7 Utah's law defines careless driving as committing a moving violation (other than speeding) while distracted by use of a handheld cellphone or other activities not related to driving.

As for the DOT’s Distracted Driving Summit, there will be a live Web cast on September 30 and October 1. Questions for the panelists will be accepted online.

Elected officials, safety advocates and others all have different opinions on the most effective way to get people to stop using phones while driving. What do you think would work?

(A) PSA videos, whether graphic (showing car accidents in gory detail) or softer ones (that invoke an emotional response)
(B) Public Safety/Driver Education
(C) Legislation and bans
(D) Socially stigmatizing the behavior (like drinking and driving)
(E) Time. People will get better at multitasking behind the wheel, so the numbers will decline on their own.
(F) None of the above. People are stubborn.