Workers assemble Volkswagen Passat sedans at the German automaker's plant in Chattanooga.

The National Right to Work Legal Defense Foundation has posted a notice aimed at Volkswagen's Chattanooga employees, saying they don't need United Auto Workers representation to talk with management about issues at the factory and offering them a petition against unionization.

"If you oppose union representation, signing and circulating such a petition against unionization is perhaps the most important thing that you can do to exercise your legal right to refrain from union representation," said a "special notice" posted on the website of the Springfield, Va., group.

The notice said that no U.S. law prohibits employees from talking with their supervisors and managers.

"Can we American workers talk with our bosses? Yes. Can we participate in a brainstorming group discussion? Yes. Can our employer set up a group and delegate full responsibility to the group to decide a workplace issue? Yes," the notice said.

It also said that employees have a legal right to refrain from signing a union authorization card. Also, the notice said a worker can revoke a union authorization card that the employee has signed.