The litigation is complex and politically charged. Among those suing are firefighters, police officers, construction workers and other responders who draw public sympathy. Many elected officials and advocacy groups are demanding compensation, long-term medical treatment and monitoring for the workers from the federal government.

Image Glen Klein, left, a former police officer who says he got sick after recovery work at ground zero, at a 9/11 rally. Credit... Allan Tannenbaum/Polaris

Mayor Michael R. Bloomberg supports a bill pending in Congress that would offer federal relief to people harmed by work at the site. But the city has, at the same time, been fighting the workers in court, arguing, among other things, that it is immune from damages in cases involving a civil defense disaster or a national emergency. At issue is how great the city’s liability would be if it lost the cases.

“We would rather stand with the responders before Congress than fight them in the courtroom,” said Jason Post, a spokesman for the mayor. “Responders and workers should not have to prove that the city or the contractors are somehow responsible for their harms — which plaintiffs are obligated to prove and which the city thinks is not the case.”

Still, in 2007, Mr. Bloomberg said the city was willing to explore settling the cases.

Although the cases have been consolidated, they are being considered separately and not as a class-action lawsuit. The court, lawyers for the plaintiffs and the city are selecting a small group of sample cases to bring to trial in the hope that the verdicts will guide settlement of the remaining lawsuits.

“No one seriously thinks that all of these cases would ever be tried,” said Richard A. Nagareda, a law professor who teaches complex civil litigation at Vanderbilt University Law School. “Ultimately, everybody understands there’s going to be some sort of comprehensive settlement. The question is, what is the price?”

The city is arguing that its liability is capped at $350 million under federal law, but lawyers for the plaintiffs are disputing that figure. If they prevail, the city could face an enormous cost for its share of the compensation. The city and its contractors are covered by an insurance fund of almost $1 billion financed by the Federal Emergency Management Agency. The private contractors named as defendants have their own insurance, although the coverage available has not been determined.