The National Labor Relations Board said Wednesday it filed a complaint against Wal-Mart Stores Inc, alleging the world's largest retailer threatened people with reprisal if they mounted strikes against the company.
The NLRB said it told Wal-Mart in November that the complaint was coming, but engaged in ultimately unsuccessful settlement talks first before filing.
In a statement Wal-Mart said it believed it acted lawfully.
"We look forward to shedding light on the facts of the situation. Again, this is just a procedural step – it provides us the opportunity to speak in front of a judge," the company said.