The Montana Supreme Court Tuesday upheld a state law cutting off worker's-compensation benefits for injured, disabled workers at retirement age.

The 5-2 ruling came in a case that insurers and businesses said would have cost them millions of dollars, had it gone the other way.

The court majority said work-comp benefits for permanently and totally disabled workers are meant to assist them for their "work life," and not into retirement.

The state law ending those benefits for disabled workers when they qualify for Social Security payments is therefore constitutional, Justice William Leaphart wrote for the majority.

"While this may not always seem fair, it is not unconstitutional," Leaphart wrote. "By acting to terminate benefits as it does, (the law) rationally advances the governmental purpose of providing wage-loss benefits that bear a reasonable relationship to actual wages lost."

He also said controlling the costs of the work-comp system is a legitimate pursuit of the Legislature, and could serve as a rationale for the law - as long as it's not the only reason.

Officials with the Montana State Fund, which writes work-comp insurance for some 27,000 businesses, had said a decision in favor of the workers could cost the fund as much as $300 million for current and future claims, as well as hiking insurance rates.

State Fund President Laurence Hubbard said Tuesday he's "quite relieved" with the decision.

"It brings some closure to an issue that we've all been concerned about for some time," he said. "This had a very large potential cost, not only to current insurance rates, but also for claims that remain open."

The state's top business lobby, the Montana Chamber of Commerce, also hailed the decision, saying it's a "legitimate government interest" to keep work-comp costs affordable for small businesses.

Jim Hunt, the lawyer representing the injured workers challenging the law, said the court order ignores constitutional protections for aging, permanently disabled workers.

"Older workers who have lost their ability to work and are consequently some of the most vulnerable people in our society have lost an important constitutional protection," he said.

The lead plaintiff in the case is Catherine Satterlee, an Anaconda woman who was a checker at Buttrey Food and Drug and hurt her back in 1992, rendering her unable to work. Her work-comp payments ended when she turned 65 in 1999.

Hunt argued that the law cutting off those benefits discriminated against Satterlee based on her age and had no rational basis for saying retirement benefit should substitute for injured-worker benefits.

Two other permanently disabled workers - James Zenahlik of Anaconda and Joseph Foster of Helena - also were plaintiffs in the case.

In a dissenting opinion, Justice Brian Morris said Social Security benefits are not the same as work-comp benefits, and therefore should not be the trigger for cutting off an injured worker's benefits.

"The court … employs a toothless analysis that permits the Legislature to advance the perfectly legitimate task of protecting the economic viability of the workers' compensation system through the illegitimate means of penalized injured workers who have qualified for Social Security," he wrote.

Morris said under the work-comp system, workers give up the right to sue for damages for on-the-job injuries, in exchange for the certainty of benefits. The state law cutting off work-comp benefits for disabled workers who qualify for Social Security "eviscerates" that deal, he said.

Justice James Nelson joined Morris in the dissent.

Justices Jim Rice, John Warner, Pat Cotter and Mike McGrath joined the majority.