BOSTON – Motorists in Massachusetts are required to wear seat belts but there's little forcing them to do so.

While the seat belt law has been on the books for decades, police must have another reason to stop a driver before writing a $25 ticket for violating it.

That’s because the state is one of 15 that only permits officers to issue a ticket for a seat belt infractions after they’ve witnessed another moving violation, such as speeding or drunken driving.

Road safety advocates cite the law as one reason Bay State motorists are among the worst in the country when it comes to buckling up.

Legislation filed by Gov. Charlie Baker seeks to change that by allowing police to stop motorists for not wearing seat belts. The proposed changes are tucked into a broader road safety bill that would also mandate hands-free cell phone use for motorists and require the ignition interlock program for first time drunken driving offenders.

Supporters say the measure would save lives and vastly improve safety on the roads.

"Seat belts are the best and most proven tool we have to cut your risk of dying in a crash by half. They are the gold standard," said Mary Maguire, spokeswoman for the American Automobile Association of New England, which supports Baker's proposal. "But we actually have one of the lowest seat belt rates in the nation, or about 80 percent of all drivers (using them).”

Massachusetts law requires all people traveling a car to wear seat belts.

Federal data underscore the benefits of seat belt use, and a government report found that a primary seat belt law could save the state millions of dollars.

The National Highway Traffic Safety Administration has found that seat belt use can lower the risk of death for those traveling in the front seats of cars by 45 percent. It also reduces the risk of non-fatal injuries by half.

At least 1,820 people were killed in auto crashes in Massachusetts between 2012 and 2016, according to the latest state data, including nine roadside construction workers.

"The numbers of fatalities and injuries where motor vehicle operators are not wearing seat belts are staggering," said state Rep. Paul Tucker, D-Salem, the city's former police chief who supports many of the provisions of Baker's bill. "I get it that sometimes people don't like government telling them what to do, but the numbers speak for themselves."

Opponents of tougher seat belt laws have raised concerns about racial profiling. Social justice groups say such measures should include requirements for police to collect demographic data regarding traffic stops to help track potential disparities in enforcement of the new laws.

Others question the need to give police more reasons to pull over motorists, given recent studies that suggest seat belt use is improving.

In the past year, seat belt use in Massachusetts rose by 8 percent, from 73.7 percent to 81.6 percent, according to the University of Massachusetts Traffic Safety Research Program.

Similar proposals have been filed in the House and Senate, but unlike Baker's bill they would increase the ticket for not wearing a seat belt from $25 to $50 per violation.

At least 34 states and the District of Columbia have primary seat belt laws that allow police to stop motorists whom they observe wearing them, according to the Governors Highway Safety Association.

New Hampshire is the only state in the nation where seat belt use is not required for adults. Children traveling in the front or back seats must wear them.

Christian M. Wade covers the Massachusetts Statehouse for North of Boston Media Group’s newspapers and websites. Email him at cwade@cnhi.com.