The Supreme Court on Wednesday cleared the way for American families whose loved ones were killed by terrorism to collect nearly $2 billion in frozen Iranian assets, but not without a warning from Chief Justice John G. Roberts Jr. that the court was squandering its power.

The justices ruled 6 to 2 that Congress had not violated the separation of powers by passing a bill that made it easier to collect the money for those whose family members were killed in the 1983 bombing of a U.S. Marine Corps barracks in Beirut and other attacks blamed on Iran.

Justice Ruth Bader Ginsburg, writing for the majority, said the court has made clear in the past that Congress may change the law during litigation even if the change will determine the outcome of a case.

Moreover, the legislature and executive branches deserve the court’s “respectful review” when the issue involves foreign policy, she said in announcing the case from the bench.

But Roberts said Congress’s action violated the separation of powers, and he was joined in his dissent by liberal Justice Sonia Sotomayor.

“At issue here is a basic principle, not a technical rule,” Roberts wrote. He said that Congress’s action had decided the case “no less certainly than if Congress had directed entry of judgment for respondents.”

He added: “Hereafter, with this court’s approval, Congress can unabashedly pick the winners and losers in particular pending cases. Today’s decision will indeed become a blueprint for extensive expansion of the legislative power at the judiciary’s expense.”

Bank Markazi, Iran’s central bank, had challenged a 2014 ruling by the New York-based U.S. Court of Appeals for the 2nd Circuit that the money, held in a New York bank, be given to plaintiffs to satisfy a judgment they won in 2007.

The suit involved survivors of 173 of the 241 killed in the Beirut attack who had secured judgments against Iran and who courts had said were entitled to more than $10 billion in compensation. When those who had secured judgments against Iran learned of bonds in a New York bank that had been frozen by the U.S. government, they went after them.

After lobbying by the families, Congress passed a law in the midst of the litigation that essentially said the victims were entitled to the funds.

The lead plaintiff in the suit was Deborah Peterson of Arlington, Va., who was seeking to avenge the killing of her brother, 20-year-old Marine Cpl. James Knipple.

The case is Bank Markazi v. Peterson.

robert.barnes@washpost.com

This article was written by Robert Barnes from The Washington Post and was legally licensed through the NewsCred publisher network.