The report—produced with a grant from State Farm—says limited research suggests cell phone use does increase crash risk, but no one knows by how much. Additionally, there is no conclusive evidence about whether hands-free cell phone use is any safer than hand-held use.

State Farm could not immediately be reached for comment.

Texting "probably" increases risk, but no evidence exists to prove if cell phone use or texting bans reduce accidents.

Therefore, among a handful of recommendations, GHSA advises states that do not have handheld bans to wait until more research is done before passing laws. In the meantime, the association urges states with bans to enforce them.

"While distracted driving is an emotional issue that raises the ire of many on the road, states must take a research-based approach to addressing the problem," Harsha says. "Until more research is conducted, states need to proceed thoughtfully, methodically and objectively."

The GHSA also recommends other measures, such as edge-line and center-line rumble strips to alert drivers when they swerve. The association asks that distracted driving be recorded in crash reports to assist in the evaluation of laws.

Based on the research it looked at, the GHSA says states should consider passing cell phone bans for novice drivers and texting bans for everyone. As of June, 30 states and Washington, D.C. prohibited cell phone use for novice drivers and 40 states and D.C. banned texting for novices, while 34 states and D.C. have enacted texting bans for all drivers.

David Snyder, vice president and associate general counsel for the American Insurance Association (AIA), characterized the reports as "somewhat internally inconsistent and confusing."

He says, "The history of auto safety proves laws are needed to promote public information and education, which leads to effective highway safety." The effects of such laws may not be immediate, Snyder adds, and the reason data is not available is because the current laws have not been enacted for long.