The National Labor Relations Board, the main federal labor law enforcement agency, issued a ruling Tuesday that will make it easier for employers to alter provisions in a labor contract without the union's permission.

In a win for employers, the board said in a case called M.V. Transportation that even if the underlying contract doesn't explicitly allow a change and the union objects to it, the employer may still adopt it.

The board had previously said that an employer had to have “clear and unmistakable" permission in a union contract to make a particular change. In Tuesday's ruling, the board voted 3-1 along party lines that changes could be allowed over a union's objection if they could reasonably infer as allowable under the "plain terms" of the contract.

"[T]he Board will examine the plain language of the parties’ collective-bargaining agreement to determine whether the change made by the employer was within the compass or scope of contractual language granting the employer the right to act unilaterally," the NLRB said. "If it was, the Board will honor the plain terms of the parties’ agreement and the employer will not have violated the Act by making the change without bargaining."

The case involved a Las Vegas transit company that attempted in 2016 to revise the work policies in a union contract. The union that represented its workers agreed to some changes, but rejected others. The company eventually went ahead with the revised policies despite the union not signing off on them. The NLRB majority argued that the move was reasonable since the company only made changes where the underlying contract was silent. "We reject any claim that the contract coverage test removes any meaningful limits on unilateral employer action," the majority said. The majority was composed of the board's three Republican members: Chairman John Ring, Bill Emanuel and Marvin Kaplan.

The board's lone Democratic member, Lauren McFerran, slammed the ruling as tossing out 70 years of precedent. "[T]he majority makes it easier for employers to unilaterally change employees’ terms and conditions of employment — wages, hours, benefits, job duties, safety practices, disciplinary rules, and more — in a manner that will frustrate the bargaining process, inject uncertainty into labor-management relationships, and ultimately increase the prospect for labor unrest," she said.