Legal Experts Say Law Allowing 9/11 Families to Sue Saudi Arabia Has Consequences

— -- American interests around the world could face serious damage as a result of a new law that empowers U.S. citizens to sue any country with a role in terrorism committed on American soil, legal experts say.

The Justice Against Sponsors of Terrorism Act (JASTA) gives families and survivors of the September 11 attacks an avenue to pursue justice in American courts against Saudi Arabia, for what they believe is its connection to the terrorist attack.

Legal experts told ABC News that JASTA, which Congress passed today over President Barack Obama’s veto, opens the U.S. to lawsuits in foreign courts brought by other countries’ citizens, threatens American interests abroad and risks rupturing diplomatic relations.

What Does the Justice Against Sponsors of Terrorism Act Do?

The law allows U.S. citizens to sue any country they allege acted in a way connected to terror acts committed in the U.S. JASTA does this by removing a legal barrier known as sovereign immunity, an ancient legal doctrine that evolved over time to shield foreign countries from being answerable in another country’s courts.

JASTA was born after families of 9/11 victims intensely lobbied for the right to sue the Saudi government. But its effect is much broader and could result in U.S. citizen-led lawsuits against any country, said Curtis Bradley, a law professor at Duke University who co-directs the school’s Center for International and Comparative Law.

"It doesn’t require that the foreign country did anything in the United States, it’s not limited to just nations known to normally be associated with terrorism,” Bradley said. “Potentially any nation could be sued.”

Could This Lead to Lawsuits Against the U.S. in Foreign Courts?

President Barack Obama opposed the bill in part because he feared foreign countries would retaliate by eroding U.S. sovereign immunity. And according to Philip Bobbitt, a law professor at Columbia University who directs the school’s Center for National Security, the president’s concern is well-founded.

The U.S. has generally avoided making foreign governments accountable to individual American citizens because of the potential of leading to a disproportionate response, Bobbitt added.

"We feel often justifiably aggrieved until we step back and look at the global nature of our interests," he said. "We see that we are so much more vulnerable than really any other state because we have businesses, and we have so many foreign bases, and because we have global interests to a degree that no other state has."

Immunity is particularly vital in the context of U.S. military activities like drone strikes that are known to have claimed innocent lives, as well as military aid to U.S. allies, Bradley said.

"I’m sure some countries would be interested in saying our military aid to Israel is aiding and abetting things that they would allege are sometimes war crimes against the Palestinians,” he said. “We normally benefit significantly by being able to say we have immunity from those kinds of claims around the world."

Laura Donohue, a Georgetown law professor who heads the school’s Center on National Security and the Law, said the U.S. has more to lose than other countries by having sovereign immunity eroded.

"This is very dangerous—and some would argue even more dangerous—than the risk to other countries because the United States has such a global presence that if we then are no longer protected by sovereign immunity elsewhere, then it raises a lot a much more difficult situation for us than it would for any other country,” she said. “So at some level, this is a huge mistake for us.”

Could This Hurt U.S. Diplomatic Relations?

Donohue said the law has potential to seriously undermine American diplomatic relations abroad, as well as weaken U.S. negotiating leverage.

"If the United States is trying to engage in a negotiation with a country at the time when its citizens are suing that country in court, it makes it more difficult for the president and the executive branch to actually engage in that negotiation," she said. "If we’re in a negotiation with another country and they have our diplomat and suddenly our diplomat is arrested on local criminal charges, they can use that as leverage in the greater negotiation between the state powers."

An unintended consequence of the new law could be to undermine U.S. counter-terrorism partnerships, Bradley noted.

"A sad irony of this bill, which I understand may have the noble purpose of helping the 9/11 victims, is that it could well undermine some cooperation between the United States and other countries designed to combat terrorism," he said. "It’s going to be harder to work with them to address the very problem we’re all worried about which is global terrorism."