As of this month, Idaho is now enforcing its new distracted driving law.
Despite tougher measures across the U.S., researchers said there's still a lot they don't know about reducing cell phone use behind the wheel.
Idaho's law bans drivers from holding cell phones while driving. Ian Reagan, senior research scientist with the Insurance Institute for Highway Safety, said most states have a distracted driving law focusing on cell phone use, but researchers haven't yet been able to clearly define how effective these laws are.
"It's really hard to really understand what the true nature of the problem is, because the phenomenon of distracted driving is -- it's hard to study," he states.
Reagan said unlike DUI cases, law enforcement doesn't always have the legal tools to investigate cell phone records, which some analysts said can be incomplete, even if they are obtained. So, Reagan believes crash data is under reported.
The National Highway Traffic Safety Administration reported more than 2,800 distracted driving fatalities in 2018. Only 385 were linked to cell phone use.
In contrast to the unreliable crash data, Reagan said some research indicates these laws have been effective in changing drivers' behavior. He said overall data might become more conclusive as states adopt clear and consistent language in these measures.
"Rather than trying to ban specific behaviors, like saying you can't text with a phone, we're starting to see laws that flat out say you can't hold the phone," he states.
Under Idaho's new law, drivers can only use the hands-free mode while driving.
Idaho law enforcement will be issuing warnings until the end of the year and start giving out citations in 2021.
Montana is the only U.S. state with no distracted driving law on the books that deals with cell phones.