A state appeals court ruled on Tuesday that the Port Authority was liable for damages caused by the 1993 World Trade Center bombing, because it knew about but chose to ignore “an extreme and potentially catastrophic vulnerability that would have been open and obvious to any terrorist who cared to investigate and exploit it.”

The ruling unanimously upheld a jury’s verdict that the agency was 68 percent liable for the bombing and the terrorists 32 percent liable. Under state rules, because the Port Authority’s liability was more than 50 percent, it can be forced to pay all the damages to injured survivors and to relatives of those killed.

In its decision, the court noted that the Port Authority, a bistate New York and New Jersey agency that owned the trade center, did not argue that the bombing was unforeseeable, only that it was unlikely, since its own consultants and an internal study group had predicted “with exact prescience” how an attack could be carried out.

Andrew Carboy, a lawyer for the plaintiffs, estimated on Tuesday that the Port Authority faced more than $100 million in damages for the 50 personal injury and dozen business-interruption cases remaining. Apart from its fiscal effect, the unanimous, 35-page decision signified the first time that a body of judges, versed in the nuances of the law and legal precedent as well as the evidence, had ruled on a seminal moment in New York history.