spate of government litigation against the nation's gun companies has been stifled in 30 states, which have passed laws granting the industry immunity from civil lawsuits.

Those laws have all been enacted since 1998, when New Orleans became the first of almost three dozen cities and counties to file suits against gun manufacturers and dealers, accusing them of being public nuisances and seeking huge damage awards in a campaign similar to that waged against the tobacco industry.

The gun companies have won the aid of state legislatures to turn back the legal assault. Already, civil suits against the industry by New Orleans and Atlanta have been dismissed by state courts in Louisiana and Georgia because of the grants of immunity, even though the grants were passed after the suits were filed.

Suits by Detroit and Wayne County, Mich., are pending while a Michigan court determines whether a new law there granting immunity can be applied retroactively.

A striking exception to the trend is the California State Legislature, which passed a bill this week repealing a law that gave the gun industry immunity.

Gun control advocates hailed the repeal as a major defeat for the industry, but their victory may be short-lived. In Washington, there is a bill with 228 sponsors in the House of Representatives, that would provide federal immunity to the firearms industry. A similar bill in the Senate has 39 sponsors. No other industry has such blanket protection.

Some of the other lawsuits have survived motions to dismiss by the gun industry and have quietly moved into the discovery phase.

Lawyers for the cities, who have subpoenaed large numbers of internal firearms company documents and testimony by industry officials, say they have now found significant evidence of their central claim — that the gun industry maintains a distribution system that allows a large number of guns to fall into the hands of criminals and juveniles.

Specifically, the lawyers say, they have found evidence that the gun manufacturers failed to act on warnings by the Federal Bureau of Alcohol, Tobacco and Firearms that certain distributors were responsible for selling large numbers of guns that ended up with criminals.

"We haven't found one of the companies that uses this information from the government to check its distributors, or put them on notice or cut them off," said David Kairys, a professor at Temple University Law School who is advising many of the cities.

But Lawrence G. Keane, the general counsel for the National Shooting Sports Foundation, the trade association for the gun industry, denied that the cities had found any damaging evidence. "If there was evidence that manufacturers were willingly selling to criminals and juveniles, the A.T.F. would close them down," Mr. Keane said.

Mr. Kairys and some other lawyers for the cities say they do not expect to win large monetary settlements. Instead, they say, the cities are hoping to force the gun manufacturers to change their distribution system to make it harder for criminals to buy guns.

Mr. Keane said he was confident the municipal lawsuits would all be dismissed or decided in favor of the gun companies.

Several other cities' lawsuits, Mr. Keane pointed out, have already been dismissed by the courts because the judges did not accept the evidence or a new legal theory that the cities are trying to use: that the gun industry amounts to a public nuisance, like an industrial polluter, because it supplies guns to criminals.

In another suit, brought by Boston, a Massachusetts judge allowed the case to proceed but lawyers for the city dropped the case after discovery was completed. One lawyer close to the case said that a law firm doing some of the work for the city dropped out when it realized there would be little money to collect.

Mr. Keane said the lawyers for Boston gave up "because they realized these cases are dogs. There is no pot of gold at the end of the rainbow."

Mr. Keane said he was confident the same result would occur in California, where 12 cities and counties have a consolidated lawsuit against the gun industry.

"The same documents were produced in Boston and California, many of the witnesses were the same, and many of the lawyers are the same," Mr. Keane said.

But Dennis Henigan, the legal director of the Brady Campaign to Prevent Gun Violence and a co-counsel in the California suits, said the situations in the Boston and California cases were very different. "We think the California cities will be able to put on a powerful case against the industry," Mr. Henigan said.

Mr. Henigan said the vote by the California Legislature this week to repeal the immunity was in response to an unpopular decision last year by the California Supreme Court ruling that victims of a rampage shooting at a law office in San Francisco in 1993 could not sue the manufacturer of the murder weapon because of the immunity law.

The new bill repealing the gun industry's immunity now goes to Gov. Gray Davis. Russ Lopez, a spokesman for Governor Davis, said the governor had not yet decided whether to sign the bill, though when the immunity law originally passed Mr. Davis voted against it as a member of the Assembly.

Andrew Arulanandam, a spokesman for the National Rifle Association, said the gun industry deserved special protection because "it is irresponsible to hold a legitimate industry responsible for the criminal actions of a few people over which it has no control."

"We would not sue car manufacturers for injuries caused by a drunk driver," Mr. Arulanandam said.