LOS ANGELES - If you've ever been pulled over by a police officer for not wearing a seat belt, there's a good chance the officer also wasn't buckled up.

While 86 percent of Americans now wear seat belts, a study that will be published by California's Commission on Peace Officer Standards and Training estimates that roughly half of law enforcement officers don't wear them.

With traffic-related fatalities the leading cause of death of officers on duty, departments nationwide are buckling down to get officers to buckle up.

"Something that can save a person's life should be on a high priority of being enforced," said Richard Ashton, a former police chief who has studied officer safety for more than a decade with the International Association of Chiefs of Police.

The Los Angeles Police Department has a new seat-belt education effort after inspector general Alex Bustamante found that up to 37 percent of officers involved in accidents in 2012 weren't wearing seat belts.

State laws mandating seat-belt use often exclude police, but the LAPD and most other departments require them in all but certain circumstances.

The costs of not doing so are clear.

In 14 of the last 15 years, it wasn't a shooting but a traffic incident that was the leading cause of officer deaths, according to the National Highway Traffic Safety Administration. Of the 733 law enforcement officers killed in a vehicle accident from 1980 through 2008, 42 percent weren't wearing seat belts.

"This is such low-hanging fruit. This fruit is on the ground almost," said Steve Soboroff, president of the Police Commission at a recent meeting of the civilian oversight board.

New recruits grew up wearing seat belts but often don't on the force because senior officers don't use them. Some cut old ones off cars and buckle them in to disable the alarm, belt them out of the way, or cut them out entirely.

Part of the problem is blamed on what experts call the myth of a "ninja assassin," an assailant whose ambush attack would leave officers vulnerable because their seat belts would interfere with their ability to get their gun.

"No one can tell you an actual story about it," Ashton said. "I haven't been able to document it at all."

LAPD Chief Charlie Beck said he prefers educating rather than punishing officers who aren't wearing seat belts, because usually it's a well-intentioned effort to more speedily help the public.