In 2001, lead plaintiff James Owens and others filed a civil lawsuit against Sudan, for its role in the attack, under the Foreign Sovereign Immunities Act with the recently-added 1996 amendments for state-sponsored terrorism. They argued that Sudan was at fault for providing sanctuary to the bombers, prior to the attack. The lawsuit was prolonged over a decade, hampered in part by the lack of Sudan sending counsel at times, but further struggled when the legal system ruled that foreign nations had sovereign immunity from cause of action in civil lawsuits based on the current language of the Foreign Sovereign Immunities Act in a 2004 case. Congress amended the Foreign Sovereign Immunities Act in 2008 to correct this and to allow its provisions to retroactively apply to existing lawsuits, including Owens' case. With that, hundreds more plaintiffs joined the suit, eventually with more than 700 parties listed. By 2014, the district court awarded the plaintiffs over $10 billion. Sudan, which had not appeared during the initial lawsuit, appealed the judgment, arguing it did not understand the US civil suit system and did not understand the consequences of not appearing, but also challenged the retroactive nature of the 2008 change to the Foreign Sovereign Immunities Act. The appeals court discounted Sudan's argument regarding its lack of understanding, and still upheld them liable for the bombings, but ruled that the $4.3 billion of punitive damages were not allowed to be applied retroactively. The plaintiffs petitioned to the Supreme Court to appeal, and in May 2020, the Court ruled in "Opati v. Republic of Sudan" that the punitive damages could be retroactively applied, restoring the $4.3 billion that had been awarded at the District Court.