The nation's largest lawyers group is taking on the biggest gun rights organization over employers' rights to bar workers from leaving guns in their cars while on the job.
The American Bar Association says the issue is workplace violence and how to reduce it.
The ABA, meeting in Miami, is expected to go on record early next week supporting the right of employers "to exclude from the workplace and other private property, persons in possession of firearms or other weapons."
Roughly 1,000 people are killed at work each year and guns are used in 80 percent of those incidents, the ABA says, citing federal estimates.
The National Rifle Association says the question is whether employees can protect themselves on their drive home.
The NRA has embarked on a state-by-state campaign to get legislatures to enact laws that require employers to allow their workers to bring guns on company parking lots.
"When you get off work at 12 o'clock or 1 o'clock and you're driving home, you have the right to protect yourself if you're accosted on the highway," said Wayne LaPierre, the NRA's executive vice president.
The issue has its roots in two unrelated episodes, the firing of employees in Oklahoma and a shooting rampage in Mississippi.
In 2002, forest products giant Weyerhauser Corp. fired eight employees after guns were found in their cars on company lots. Federal courts have upheld the firings.
In response, the Oklahoma Legislature passed a law that would prevent business owners from prohibiting guns inside locked vehicles on company property.
Houston-based ConocoPhillips Inc., which employs more than 3,000 people in Oklahoma, filed a federal lawsuit in an effort to block the law. The issue is pending in the courts.
The NRA, meanwhile, began a boycott of the energy company's Conoco and Phillips 66 products and stepped up efforts to get other states to adopt laws similar to Oklahoma's.
After the Weyerhauser firings, but before the Oklahoma law was enacted, a workplace shooting case occurred that gun-control advocates and businesses point to as a clear example of why guns should be kept far from the factory or office.
In July 2003, Lockheed Martin employee Doug Williams abruptly left a training session at the company's Meridian, Miss., plant and retrieved a shotgun and semiautomatic rifle from his truck in the employee parking lot.
He opened fire on employees, killing six and wounding eight.
Afterward, authorities retrieved three more guns from his truck.
"Unfortunately, this is an all-too-common event," said Brian Siebel, senior attorney at the Brady Center to Prevent Gun Violence. "A gun is available in the parking lot for an employee who may be unstable and who reaches a snapping point. This should be a no-brainer."
But LaPierre said that people in 38 states can legally carry guns in their cars. Federal law permits people to transport guns between states for hunting and other purposes, he said.
If company restrictions were applied broadly, gun owners' rights would be unlawfully limited, LaPierre said.
"In effect, you're nullifying the right to carry," he said. "People could drive on their highways with the guns, but they couldn't stop anywhere."
Alaska, Kentucky, Minnesota and Mississippi all have adopted laws that limit employers from barring guns to varying extents.
But the NRA lost legislative battles in several states last year, including Florida and Georgia among states traditionally friendly to gun rights. In those states, business groups mounted unexpectedly strong opposition to the proposals.