In a ruling Thursday, the Court of Appeals was divided 4-3 in reversing lower courts.
The majority conclude that the Port Authority of New York and New Jersey, which runs area airports and owns the trade center site, is entitled to government immunity for its security measures at the building.
A jury found the agency failed as a mainly commercial landlord to maintain reasonably safe premises and was 68 percent at fault, blaming terrorists for the other 32 percent.
A midlevel court upheld that ruling.
About 200 claims in the case were filed. Most have been privately settled.
