Andrew Francis Wallace/ZUMA

Nearly four years ago, while lifting pallets of blankets during an overnight stocking shift at Walmart, Barb Gertz began to notice a dull pain in her arms. She kept on lifting and stocking, but by the time her lunch break rolled around she could no longer raise her arms. Her doctor told her she had tendinitis in her biceps, and that it was most likely caused by her job. Walmart disagreed. The retailer contested Gertz’s workplace-injury claim—and won.

If Gertz had worked in a factory, she could have bolstered her case with evidence from the Occupational Safety and Health Administration’s national database of manufacturing workplace injuries. But no such database exists for retail workers like Gertz. A new regulation that OSHA is scheduled to finalize this year would change that. OSHA wants to create a public database of workplace injury and illness data from all industries, not just manufacturing. This would help workers, the government, researchers, and journalists identify companies with safety problems. But the trade groups that represent some of America’s biggest chains—including Walmart, Target, and McDonald’s—are fighting back hard.

The National Retail Federation—a group that represents Walmart, McDonald’s, and The Container Store—spent $2.4 million lobbying on this measure and other issues between January and September of last year. In a letter to OSHA last March, the group complained that the rule would require…