The US Congress has rejected a veto by Barack Obama for the first time since he became president.
The House voted 348-77 on Wednesday to override his veto of legislation and allow the families of September 11 victims to sue Saudi Arabia for the kingdom’s alleged backing of the attackers.
The Senate had voted 97-1 to override his veto.
The lawsuit legislation now becomes law despite elements that Mr Obama and top Pentagon officials warn could put US troops and interests at risk.
Several lawmakers who voted for the legislation acknowledged the defects could trigger lawsuits from people in other countries opposed to US policies and military actions.
However, proponents said the bill is narrowly tailored and applies only to acts of terrorism that occur on US soil.