Earlier this year, the U.S. Department of Labor (DOL) issued revisions to the Fair Labor Standard Act’s overtime pay regulations. The final rule was set to increase the standard threshold for overtime eligibility to $47,476 — instead of the $50,440 figure originally proposed. This new threshold would have been the first significant change in four decades. It was one of President Obama’s signature achievements for boosting wages and was scheduled to take effect on December 1.

However, overnight, U.S. District Judge Amos Mazzant, in Sherman, Texas, ruled in agreement with 21 states and a coalition of business groups, including the U.S. Chamber of Commerce, that the proposed rule is unlawful and granted their motion for a nationwide injunction.

According to Reuters reports, Mazzant, who was appointed by President Barack Obama, ruled that the federal law governing overtime does not allow the Labor Department to decide which workers are eligible based on salary levels alone.

The Fair Labor Standards Act says that employees can be exempt from overtime if they perform executive, administrative or professional duties, but the rule “creates essentially a de facto salary-only test,” Mazzant wrote in the 20-page ruling.

Various state and business groups that originally challenged the rule applaud the decision. But the Labor Department strongly disagrees and remains confident that the entire rule is legal.

Reports indicate that the Labor Department can appeal to the New Orleans 5th U.S. Circuit Court of Appeals, but might also drop the appeal after President-elect Donald Trump takes office in January.

Back in August, Trump commented that the overtime rule was an example of the type of burdensome business regulations he would seek to roll back as president, perhaps by exempting small businesses or delaying implementation.

Even if the rule survived the legal challenge, it could be upended by legislation passed by Congress or withdrawn by Trump’s Department of Labor.