Dozens of law firms had their hands in the sprawling litigation that stemmed from the Sept. 11, 2001, attacks on the World Trade Center in New York City.

They represented a sweeping array of entities: first responders seeking compensation for exposure to contaminants at the site, the owner of the towers looking to collect from the airlines that let the hijackers on board, victims looking to haul the government of Saudi Arabia into U.S. court, and others.