In explaining the rationale for the new rule, the agency said in a statement that it sought to return to the joint-employer doctrine that prevailed for decades before 2015, except “with the greater precision, clarity and detail that rule-making allows.”

But the new rule could make it even less likely for companies to be deemed joint employers than before 2015 because it adds the word “substantial” to the words “direct and immediate” in describing the form of control that determines that status.

In January, the Labor Department announced a similar rule effectively making it more difficult to hold parent companies liable for minimum wage and overtime violations committed by franchisees.

The labor board, which gained a Republican majority in 2017, first sought to reverse the Obama-era standard in a ruling late that year. But the board voted to vacate that ruling after its inspector general found that a Republican board member had a potential conflict of interest and should not have taken part.

After that reversal, the board took a new tack. Instead of trying to change the Obama-era standard by deciding cases involving specific employees and employers, it decided to issue a regulation that would apply to all employees and employers in these kinds of work arrangements.

Philip A. Miscimarra, who was the board’s chairman during its first effort to reverse the Obama-era policy in 2017 and left soon after, said that it was appropriate for the agency to address the issue through a new regulation. “The board clearly has statutory authority to adopt regulations, and rule-making can provide more certainty in this important area for employees, unions and employers,” Mr. Miscimarra said in an email.

Critics of the board, however, argued that the agency was doing whatever it could to achieve a desired policy outcome.