The court declined Monday to consider an appeal of a decision in a case known as Sokolow v. Palestine Liberation Organization. The plaintiffs won $656 million in a 2015 federal jury verdict, but it was overturned a year later by an appellate court.

The court upheld that appeal.

The lead plaintiff, Mark Sokolow, his wife and two of his daughters were injured in a Jerusalem suicide bombing in 2002 that killed an 81-year-old man. His fellow plaintiffs are families of victims of terrorist attacks in Israel that killed 33, including several Americans, and wounded over 450.

Their suit argued that the late PLO Chairman Yasser Arafat had paid attackers and their families, and that they had standing to sue his organization under the 1992 Anti-Terrorism Act.

Susan Tuchman, the director of the Center for Law and Justice of the Zionist Organization of America, said in an email that the Supreme Court’s decision was a “terrible blow” for those seeking to hold backers of terrorism accountable.

“I’m not sure how, in the future, most terror victims will be able to proceed successfully with a suit under the Anti-Terrorism Act,” she said.

Several administrations, including President Donald Trump’s, worried that such lawsuits could undermine American foreign policy interests. U.S. Solicitor General Noel Francisco sided with the PLO in February, drawing rebukes from conservatives, including some of the Trump administration’s most steadfast Jewish community defenders. Lawmakers in Congress from both parties had urged the Trump administration to back the plaintiffs.

“The United States has in effect assented to the jurisdictional hurdles imposed by the [appeals court], which will prevent many if not most victims of international terrorism from suing to hold their terrorist attackers accountable,” the ZOA said at the time.

Sokolow told JTA in an interview at the time that he was shocked by the solicitor general’s filing, citing Trump’s invocations of “America first” when it comes to foreign policy.

The Trump administration said last month that it “sympathizes deeply” with the families, but the case does not meet the standards for Supreme Court review.