The Philadelphia law firm Cozen O'Connor sued Saudi Arabia and several Islamist charities in 2003, seeking to hold them financially liable for the 9/11 terror attacks.

Although the Saudis' lawyers won earlier rounds when a judge removed the kingdom and Saudi royals as defendants, the case has been appealed to the U.S. Supreme Court. Moreover, a number of the Saudi charities remain as defendants.

Whichever way the court rules, the story behind the suit is a case study in tort law with foreign-policy implications - and billions of dollars at stake.

A two-part Inquirer series – and follow-up articles - trace events that preceded the Sept. 11, 2001, attacks, and leads to a federal courtroom.

Part 1: Pinning the blame for 9/11

It is here that the Cozen O'Connor law firm has filed an 812-page lawsuit on behalf of U.S. and global insurance companies alleging that Saudi Arabia and Saudi-backed Islamist charities nurtured and financed al-Qaeda, the author of those deadly attacks. Read the article

Part 2: How Cozen took on a kingdom for 9/11 liability

That is what led Stephen Cozen's firm to file an 812-page complaint that would seek to hold America's closest ally in the Arab world financially liable. Read the article

A former al-Qaeda fighter accuses a Saudi charity

But that assertion is disputed by a former al-Qaeda commander who testified in a United Nations war-crimes trial that his unit was funded by the Saudi High Commission for Relief of Bosnia and Herzegovina, which was founded by the Saudi government. Read the article

Law's exceptions allow citizens to sue foreign nations

While the 1976 Foreign Sovereign Immunities Act broadly protects foreign governments against lawsuits filed by U.S. citizens, the act provides exemptions, and federal judges have allowed suits to proceed in two notorious cases involving state-sanctioned assassinations. Read the article

Cozen O'Connor dealt blow in 9/11 lawsuit

Aug. 15, 2008: An ambitious lawsuit by the Philadelphia firm of Cozen O'Connor blaming the government of Saudi Arabia for the Sept. 11, 2001, attacks was dealt a sharp setback yesterday when a federal appeals court ruled that the desert kingdom could not be sued for acts of terrorism. Read the article and read the ruling

Another tack in terror-financier lawsuit

Aug. 20, 2008:  Only days after suffering a significant setback in their lawsuit against Saudi Arabia, lawyers at Cozen O'Connor and other plaintiffs' lawyers have opened a new front in their battle to hold terrorism financiers accountable for the Sept. 11, 2001, attacks. Read the article

U.S. high court gets 9/11 appeal

Nov. 14, 2008: Thousands of victims of the 9/11 attacks appealed to the Supreme Court yesterday, asking it to overturn a lower court decision barring lawsuits against Saudi Arabia for supporting acts of terrorism. Read the article

Saudi filing faults Cozen suit

Jan. 6, 2009: In papers filed with the U.S. Supreme Court, lawyers for the kingdom and several high-ranking Saudi royals say that U.S. law provides blanket immunity to Saudi Arabia from lawsuits over the 9/11 attacks. Read the article

Solicitor General is asked to weigh in on 9/11 suit

Feb. 24, 2009: The request from the U.S. Supreme Court may indicate a close hearing. Read the article

High court is urged to block 9/11 suit against Saudis

May 29, 2009: In a setback for insurers and individual victims of the 9/11 attacks, U.S. Solicitor General Elena Kagan urged the Supreme Court yesterday to reject allegations that Saudi Arabia was responsible because it indirectly financed al-Qaeda and other terrorist groups. Read the article

The 9/11 suit against the Saudis, and politics

June 9, 2009: The case is likely to reach a critical juncture this month when the U.S. Supreme Court is expected to decide whether to hear arguments on Saudi Arabia's legal exposure. Read the Law Review column

Phila. firm files brief on behalf of 9/11 victims

June 11, 2009: In a stinging rebuke to the Obama administration, lawyers representing victims of the 9/11 attacks accuse the government of trying to "appease" Saudi Arabia by urging the Supreme Court not to hear arguments that the kingdom could be sued for its alleged role in funding the attackers. Read the article

More Saudi ties

June 26, 2009: A Defense Department intelligence document on weapons trafficking in Somalia suggests a prominent Saudi government charity supplied arms and other aid to a Mogadishu warlord whose forces killed 18 U.S. soldiers in the notorious Black Hawk Down battle in 1993. Read the article

Court filings advance claim Iran aided 9/11 hijackers

May 20, 2011: Lawyers for seven family members of Philadelphia-area victims of the Sept. 11, 2001, attacks filed new documents Thursday in long-running litigation that they say provide clear evidence the government of Iran aided the hijackers. Read the article

New lawsuit alleges Saudis aided 9/11 attacks

Nearly 10 years to the day after the attacks of Sept. 11, 2001, a London-based insurance syndicate Thursday filed a new lawsuit against the government of Saudi Arabia in U.S. District Court in Johnstown, Pa., alleging that the Saudis helped finance and provided logistical support to Islamist terror groups. Read the article

Timeline: Evolution of the Lawsuit

This time line draws on events that arise from the 9/11 attacks. View the timeline (.pdf)