The 2nd US Circuit Court of Appeals in Manhattan said the Communications Decency Act, a 1996 law regulating internet content, shielded Facebook from liability. It also declined to exercise jurisdiction over the plaintiffs’ foreign law claims.
Lawyers for the plaintiffs did not immediately respond to requests for comment. Facebook and its lawyers did not immediately respond to similar requests.
The plaintiffs also included relatives and the estates of Hamas victims.
Wednesday’s decision upheld a May 2017 ruling by US District Judge Nicholas Garaufis in Brooklyn.
It is a fresh setback to efforts to hold companies such as Facebook and Twitter liable for failing to better police users’ online speech.
The US Department of State has designated Hamas as a foreign terrorist organization since 1997.
The case is Force et al v Facebook Inc et al, 2nd US Circuit Court of Appeals, No. 18-397.