Volkswagen has joined other large companies and a chorus of business groups and Republican lawmakers in challenging a union strategy of organizing splinter groups of workers, but experts say recent court decisions approving the tactic suggest it is here to stay.

The German automaker’s U.S. subsidiary earlier this month brought a case in a Washington, D.C.-based federal appeals court seeking to overturn a vote by a group of skilled trade workers at its Chattanooga, Tennessee, assembly plant to join the United Auto Workers (UAW).

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Courts that have signed off on smaller bargaining units have ruled federal law favors unions’ proposed bargaining units as long as they are appropriate. Ensuring workplace peace is not a requirement of the law, said William Gould, a professor at Stanford Law School who was the NLRB’s chairman under President Bill Clinton.

“To the extent that you balkanize the workforce, you have the potential for more conflict,” he said. “But that simply does not determine whether a unit is appropriate.”