World Trade Centre leaseholder Larry Silverstein's battle with 20 leading insurers is set to resume later today.
The biggest corporate dispute to emerge from the
11 September attacks will reach a critical stage as Silverstein continues his claim for $7bn (£4.4bn) in insurance payouts. He claims the destruction of the Twin Towers represents two separate events.
Silverstein's insurers, led by Swiss Re, counter that the attacks formed a single event, worth only one claim of about $3.5bn (£2.2bn).
A three-judge panel at the US Court of Appeals is scheduled to listen to arguments from both sides.
The case is expected to close later this month.
