DES MOINES — A district judge heard arguments Friday from attorneys representing the state and its largest public employee union over Iowa’s new collective bargaining limits.

Judge Arthur Gamble, who heard from the state of Iowa and from AFSCME Iowa Council 61, which represents roughly 40,000 public workers, gave no time frame for making a ruling.

The union sued the state over the new law, which significantly reduced the benefits for which many public employees can collectively bargain. The law was approved earlier this year by the Republican-led Iowa Legislature and signed into law by then-Gov. Terry Branstad.

The union’s lawsuit is based on its assertion that the law creates separate classes of public employees by removing collective bargaining elements for some but not for others, like first responders.

“It’s offering a privilege to people and not to everyone in similar circumstances,” union attorney Mark Hedberg told the judge.

Hedberg also asserted the law’s definition of public safety employees — many of whom were protected from the reduced collective bargaining rights under the new law — is faulty because it excludes positions like campus police and corrections officers, but includes park rangers.

Matt McDermott, on behalf of the state, argued the new law does not violate the state constitution and pointed to court decisions that upheld Wisconsin’s 2011 collective bargaining changes. McDermott said Wisconsin’s law provided a template for Iowa’s.