Robert P. Hartwig, the president of the Insurance Information Institute, said that insurance generally covered accidents and unintentional acts — not intentional or illegal ones. “Insurance will cover you if your home burns down in an electrical fire, but it will not cover you if you burn down your own house, and you cannot insure yourself for arson,” he said.

Some claims stemming from shootings have been covered by homeowners’ insurance — even by policies that said they did not cover illegal acts.

The families of the two students responsible for the 1999 killings at Columbine High School in Colorado were able to use money from their homeowners’ policies to settle a lawsuit brought by families of most of the victims. In 2001, a California court ordered an insurance company to defend a policyholder whose 16-year-old son shot and killed a friend with a Beretta handgun that he had found in his mother’s coat. But the year before, a North Carolina court ruled that an insurance company did not have to cover the expenses of a policyholder who had shot and wounded a prowler on his property.

Christopher J. Monge, an insurance agent and gun owner in Verona, Wis., recently wrote a book, “The Gun Owner’s Guide to Insurance for Concealed Carry and Self-Defense,” which he sells at gun shows. Mr. Monge said that the problem with most liability insurance is that it promises coverage only in cases of a gun owner’s negligence, or an accidental shooting — and not if the gun owner shoots someone intentionally in self-defense. “A negligent act is covered by your liability policy, but if you intentionally shoot somebody, it could be excluded,” he said.

So as more states pass self-defense laws, Mr. Monge said that he found several insurance companies that would specifically offer liability coverage in cases of self-defense, usually in the form of an “umbrella” policy that added a higher level of coverage than the routine coverage for negligence in a homeowners’ policy. An umbrella policy adds coverage for unusual, but potentially expensive, incidents.

But he opposes proposals to make liability insurance mandatory. “They’re barking up the wrong tree, if you ask me,” he said. “Ninety-nine percent of gun owners are going to be safe and not go crazy.”