A group of 16 US senators have renewed a bipartisan effort to curtail the ability of countries to invoke sovereign immunity in lawsuits accusing them of supporting terrorism — a move aimed in large part to clear the way for long stymied legal claims about Saudi Arabia's alleged complicity in the 9/11 terror attacks to proceed.

On Thursday, Sen. Charles Schumer (D-NY) and Sen. John Cornyn (R-TX) reintroduced the Justice Against Sponsors of Terrorism Act (JASTA). This is the third time the bill has been submitted since 2011. The Senate passed it last December, but it stalled in the House. There is hope that the time has finally come for Congress to approve it. The latest version is co-sponsored by 14 other senators, including Al Franken (D-MN), Diane Feinstein (D-CA), Ted Cruz (R-TX), and Jeff Flake (R-AZ).

JASTA would retroactively affect any civil action "arising out of an injury to a person, property, or business on or after September 11, 2001." In statements accompanying the announcement, both Schumer and Cornyn associated the bill with litigation related to the attacks.

Survivors and victims' families filed several lawsuits against the Saudi Arabian government and entities within the kingdom in the years following 9/11. Those lawsuits were consolidated in New York federal court in early 2004, with the plaintiffs identified as a group called 9/11 Families and Survivors United for Justice Against Terrorism. In the decade since then, Saudi Arabia's lawyers have been able to drag out the case by claiming sovereign immunity and denying that evidence in the case presents a clear "tort exception" in the Foreign Sovereign Immunity Act (FSIA).

A tort act under FSIA is considered a harmful act committed inside the United States. Lawyers for the plaintiffs insist that agents of the Saudi government operated in the US and that Saudi charities acted as collaborators in the attacks. They say that a focus on the tort rule forestalls a thorough discussion of lawsuit's central claim: that members of the Saudi government were involved in the planning of 9/11. JASTA would amend FSIA and prevent accused foreign sponsors of terrorism from invoking sovereign immunity in cases involving terrorist acts occurring in the US.

"The bottom line is that victims of terror on American soil ought to have an ability to hold accountable the foreign powers and other entities that fund the hate-filled organizations that inflict injury and death on our fellow citizens," Schumer said in a statement. "Unfortunately, our courts have prevented that and allowed countries like Saudi Arabia that have provided financial support to terror-linked operations to escape any repercussions."

Saudi Arabia, a stalwart US ally in the Middle East, has always denied involvement in the al Qaeda plot.

"The idea that the Saudi government funded, organized, or even knew about September 11 is malicious and blatantly false," Prince Bandar bin Sultan, a member of the royal family and an ambassador to the US from 1983 to 2005, said in 2003. "There is something wrong with the basic logic of those who spread these spurious charges. Al Qaeda is a cult that is seeking to destroy Saudi Arabia as well as the United States. By what logic would we support a cult that is trying to kill us?"

The kingdom points to the findings of the 9/11 Commission, which stated that it had "found no evidence that the Saudi government as an institution or senior Saudi officials individually funded" the terrorist organization. But many current and former American officials with knowledge of classified materials concerning 9/11 say that the use of that line to exonerate Saudi Arabia is problematic and misleading due to the limitations of the commission's investigation and the mass of intelligence that remains classified.

'The central thesis is that certain elements of the Ministry of Islamic Affairs used the government platforms available to them to channel resources to al Qaeda.'

Lawyers for victim's families and survivors assert that other evidence proves their case, and have introduced damning affidavits from two members of the commission and the co-chair of a separate Senate investigation to back their claim. Each of the men who provided affidavits, former Secretary of the Navy John Lehman, former Sen. Bob Kerrey, and former Sen. Bob Graham, say that the 9/11 Commission did not conclusively rule out the role of individuals either within or with ties to the Saudi government.

In court, however, the Saudis' central argument remains that they cannot be sued in the first place due to FSIA.

Graham, who co-chaired the Senate's Joint Inquiry Into Intelligence Community Activities Before and After the Terrorist Attacks of September 11, 2001, has led calls for the release of a 28-page portion of the inquiry's report that was almost entirely redacted by President George W. Bush's administration on national security grounds, which he says explicitly implicates the kingdom.

"What I can say is that it's primarily the topic of who financed 9/11, that it points a strong figure at Saudi Arabia," Graham told VICE News.

In an affidavit filed this past February, Graham was more explicit.

"I am convinced that there was direct line between at least some of the terrorists who carried out the September 11th Attacks and the government of Saudi Arabia, and that a Saudi government agent living in the United States, Omar al Bayoumi, provided direct assistance to September 11th hijackers Nawaf al Hazmi and Khalid al Mihdhar," Graham wrote. "Based on the evidence discovered by the Joint Inquiry, I further believe that al Bayoumi was acting at the direction of elements of the Saudi government and that an official from the Islamic and Cultural Affairs of the Saudi Consulate in Los Angeles, Fahad al Thumairy, likely played some role in the support network for the September 11th Attacks."

Lawyers for Saudi Arabia, referring to wording in the 9/11 Commission report, have dismissed this account as "speculation," and say that the plaintiffs "have no evidence that Fahad al Thumairy did anything to help al Hazmi or al Mihdhar."

Like Graham, the families suing Saudi Arabia also allege that charities with links to the Saudi government played a significant role in financing al Qaeda in the years leading up to 9/11.

"The central thesis is that certain elements of the Ministry of Islamic Affairs used the government platforms available to them to channel resources to al Qaeda," Sean Carter, one of the lawyers representing plaintiffs, told VICE News.

Carter said that Saudi immunity has no merit and that the lawsuit should be able to proceed based on existing laws.

"JASTA would make that absolutely clear, by plainly and explicitly foreclosing the tenuous immunity arguments that the kingdom is clinging to at this point in a desperate effort to avoid having to confront the compelling body of evidence the 9/11 families have presented," he said.

In June, the CIA declassified a report issued by its Inspector General in 2005. In a heavily redacted portion of the findings, the Inspector General writes that, like the 9/11 Commission, it had "encountered no evidence" that Saudi Arabia's government "knowingly and willingly supported" al Qaeda terrorists.

Graham says that murkier connections between Saudi officials, al Qaeda, and the hijackers remain. Indeed, the Inspector General's investigation refers to a 1999 CIA intelligence report that cited "limited" reporting suggesting that "a few Saudi Government officials may support" former al Qaeda chief Osama bin Laden, himself a member of one of the country's most prominent families. The investigation also reported that "a few" intelligence officers also speculated that "dissident sympathizers within the government may have aided al-Qai'da," but ultimately concluded that the intelligence was "too sparse to determine with any accuracy" that financing of al Qaeda took place.

"I didn't see any statement there that was new as far as the unanswered question of whether there was a support network that assisted the hijackers financially," Graham said. "We are still largely being denied access to that material."

Carter says the families have been similarly stymied.

"In the past decade or so, we've tried through literally hundreds of FOIA requests to obtain relevant documents about Saudi-based support for al Qaeda," he explained. "At most, we get incredibly redacted documents from the CIA and other agencies which include some high-level statement that there were wealthy Saudi sponsors of al Qaeda, but all the details are redacted. That remains true all these years after 9/11. It's a systemic problem."

In a separate affidavit, also filed in February, John Lehman criticized the Saudi government's use of the 9/11 Commission's report to exonerate itself.

"Contrary to the view advocated by the Kingdom, the 9/11 Commission did not exonerate Saudi Arabia of culpability for the events of September 11, 2002, or the financing of al Qaeda in the years leading up to the September 11th attacks," wrote Lehman. "In addition the Kingdom is fundamentally incorrect in suggesting that our Commission in some way 'considered and rejected as factually untrue' the allegations or claims that have been advanced by the 9/11 plaintiffs against Saudi Arabia."

Like Graham, Lehman said he was troubled by evidence gathered on hijackers Nawaf al Hazmi and Khalid al Mihdhar after their arrival in Southern California. Both men point to the role of Omar al Bayoumi and Fahad al Thumairy, a Saudi cleric who was based at the country's consulate in Los Angeles. Lawyers for Saudi Arabia reject the claim that Bayoumi was an intelligence agent of Saudi Arabia.

"I was (and remain) equally disturbed by the evidence our Commission developed concerning 'charity' payments that issued from an account associated with members of the Saudi Embassy to persons closely associated with al Mihdhar and al Hazmi," wrote Lehman.

"By the time our Commission began its work," he added, "it was already well known in intelligence circles that the Islamic Affairs Department of Saudi Arabia's diplomatic missions were deeply involved in supporting Islamic extremists."

In a third affidavit filed in 2012, Kerrey, who co-chaired the 9/11 Commission, wrote that contrary to Saudi contentions, "significant questions remain unanswered concerning the possible involvement of Saudi government institutions and actors in the financing and sponsorship of al Qaeda, and evidence relating to the plausible involvement of possible Saudi government agents in the September 11th Attacks has never been fully pursued."

Kerrey also noted that the 9/11 Commission was hamstrung by its broad mandate, which required it to carry out an investigation of "historic scale." In a preface to its report, the commission cautioned that "we have not interviewed every knowledgeable person or found every relevant piece of paper. New information will inevitably come to light."

In court briefings filed in New York, lawyers for Saudi Arabia claim that the affidavits are hearsay and contend that the charities named in the suit are "not instruments of the Kingdom."

Lawyers for Saudi Arabia also called into question testimony gathered from Zacarias Moussaoui, a convicted al Qaeda conspirator who is said to have been the intended 20thhijacker on 9/11. He told lawyers for the victims' families that he met on several occasions with high-level Saudi officials in his capacity as an officer for the terrorist group.

"After 12 years, they have failed to turn those inflammatory and irresponsible accusations into viable claims supported by evidence sufficient to defeat the Kingdom's and the SHC [Saudi High Commission]'s presumptive immunity from suit," wrote the lawyers. "Plaintiffs can offer no document or witness that supports their attempt to invoke this Court's jurisdiction."

Those who have seen the classified 28 pages of the Joint Inquiry that are in dispute believe their declassification could buttress the plaintiffs' lawsuit.

"I'll tell you, the 28 pages will be an embarrassment to the previous administration," Rep. Walter Jones told VICE News last year. "We live in a world where there are certain leaders in certain countries that some people are concerned of their reaction. I feel differently."

A bill aimed at having President Barack Obama make that section of the joint inquiry public has been introduced in both the House and Senate. Though some experts caution that the pages might not offer the revelation that plaintiffs hope for, members of Congress who have reviewed them say that their declassification would not endanger US national security.

"If it was a national security issue, I would tell you up front," Jones said.

Relatives of 9/11 have claimed that Obama had privately pledged to unredact the material. Last year, he ordered an intelligence community review of their status. But they remain classified, to the frustration of those pushing for their release.

"Fourteen years later, it is shameful that we still do not have a full accounting of the facts and circumstances surrounding the most horrific terrorist attack on American soil," Rep. Stephen F. Lynch (D-MA), one of the co-sponsors of the House declassification bill, told VICE News. "The innocent victims, their families, and the American public deserve complete transparency from their government about 9/11, and the best way forward would be to declassify the 28 pages from the bipartisan congressional report."

JASTA is not without controversy. In Schumer and Cornyn's joint statement, the senators make clear the bill aims to encompass the gamut of what they consider state-sponsors of terror. For instance, Hamas, which the US has designated a terrorist organization, has been openly financed by Qatar. Like Saudi Arabia, Qatar is an American ally, and hosts the largest US air base in the Middle East. Both are members of the American-led coalition against the Islamic State insurgency.

In addition to addressing questions of sovereign immunity, the bill would amend the 1990 Anti-Terrorism Act "so that civil suits against foreign sponsors of terrorism can be held accountable in US courts where their conducts contribute to an attack that kills an American. The legislation is also couched in a wider discussion of the war on terrorism, and whether funding of a group's political arm, for instance, constitutes support of its militant elements.

For the families suing Saudi Arabia, the act would help speed up a slow-moving process that has already taken up two presidencies and could easily continue into the next decade.

Terry Strada, the national chair of 9/11 Families and Survivors United for Justice Against Terrorism, which is bringing suit against Saudi Arabia, said she hopes Obama will eventually sign JASTA and that he will act to release the 28 pages, as promised, before the end of his presidency.

Strada's husband, Tom, was a bond trader at Cantor Fitzgerald when he as killed on 9/11. At the time of his death, the couple had three young children, including a newborn baby.

"He called me that morning — he called me twice," she said. "Once before the plane hit the second tower, and a second phone call after the plane hit the building."

"The lawsuit is for justice," she added. "The 28 pages is for the truth."