The families of 9/11 attack victims will be allowed to sue Saudi Arabia, a US federal judge in New York ruled on Thursday, in a move that opens the kingdom up to a potentially embarrassing and costly civil court case.

US district judge George Daniels, in a 45-page opinion, rejected Saudi Arabia’s effort to claim sovereign immunity, saying that while the kingdom “attempts to offer seemingly innocent explanations or context, they are either self-contradictory or not strong enough to overcome the inference” that Saudi Arabia employed two men to assist the hijackers involved in the attacks.

Daniels found that the plaintiffs, the families of the 9/11 victims, offered credible evidence that two men, Omar al-Bayoumi, an accountant for a Saudi aviation company, and Fahad al-Thumairy, a diplomat stationed in the Saudi consulate in Los Angeles, had a role in assisting the hijackers.