WASHINGTON — The Supreme Court heard arguments Wednesday to determine whether $1.75 billion in Iranian assets frozen in a U.S. bank will remain in Iran’s possession or go to families of victims killed in the 1983 Marine barracks bombing in Lebanon and the 1996 Khobar Towers bombing in Saudi Arabia, both allegedly supported by Iran.

But the case not only involves compensation for victims’ families. It hinges on whether a law passed by Congress that aimed to ensure Iran would have to pay the damages violates the separation of power between the legislative and judicial branches of government.

Deborah Peterson filed a wrongful death lawsuit against Iran after her brother, Lance Cpl. James C. Knipple, was killed in the barracks attack in Beirut in which more than 200 Marines were killed. Several families of victims from the Khobar Towers attack, in which 19 Americans died, later joined her suit.

Iran has denied its involvement in both attacks, but it has been linked to the groups held responsible for the bombings.

After Iran refused to enter the case to defend itself, the families were awarded $1.75 billion in Iranian funds that are in a New York account at Citibank.

But President Barack Obama had issued an executive order freezing all Iranian assets in the Unites States to ensure Iran didn’t move it elsewhere, which also had the effect of preventing the families from receiving their damages. Later, Congress passed a law that thawed all of Iran’s assets in the U.S. and directly awarded compensation to the 19 groups of victims listed in the lawsuit.

Jeffrey Lamken, who represented Iran’s interests, said Congress violated the separation of powers by passing a law that aimed at influencing the outcome of a specific legal case. If the justices rule in favor of the victims, Lamken said, it would give Congress the power to decide court cases through legislation.

“When it comes to a suit between two private parties…that is the domain of the courts, not Congress,” he said.

However, Theodore Olson, who represented the victims’ families, argued that the law was not targeted at one case because there are 19 groups suing and because Congress thawed all of Iran’s assets, not just the amount needed to pay the victims’ groups.

“This is one case, one judge and one decision only,” Lamken fired back, referring to the mutual defendant – Iran — involved in all 19 claims.

Ruling in favor of the victims’ families would usurp the power of the judiciary and tell Americans that if they want to win a case in court, “don’t hire a lawyer, hire a lobbyist,” he said.