Last week, 60 business groups and four states joined the fight against the Department of Labor’s new overtime rule by filing amicus briefs in the Fifth Circuit asking the court to uphold the district court’s injunction blocking the rule from taking effect.

Leading the way for the states was Missouri Attorney General Josh Hawley, whose office authored the states’ brief. In their brief, the states argue that the new overtime rule undermines state sovereignty. In a statement, Hawley said that the overtime rule, if implemented, would hurt the Missouri economy. The rule would expand overtime protections, more than doubling the salary-level threshold for employees to be exempt from overtime.

“I look forward to seeing President Trump roll back these illegal, last-minute regulations,” he said. “Missouri is ready to fight in court to protect our workers and businesses.”

The total number of states challenging the rule now sits at 25. The states that joined Missouri in its brief are Colorado, Montana and Wyoming.

The business groups, in their brief, argued that the Fair Labor Standards Act does not allow the DOL to make such a drastic change to the overtime exemption and that the new rule overly relies on workers’ salaries as the basis for overtime exemption rather than their job duties.

The DOL’s final brief is due Jan. 31, after which oral argument will be set. Due to fears that the Trump administration will abandon defense of the overtime rule, the Texas AFL-CIO has filed a motion to intervene in the lawsuit so that it can argue in favor of the rule should the administration so decline.