In May, Carolyn McCarthy, a nine-term congresswoman from Long Island, was diagnosed with lung cancer. Her treatment began almost immediately, causing her to take a lengthy absence from her office while she fought the disease. At the same time, McCarthy, 69, ended a pack-a-day cigarette habit that she’d had for most of her life, presumably because she understood the link between cigarette-smoking and lung cancer. Scientists estimate that smoking plays a role in 90 percent of lung cancer deaths.

“Since my diagnosis with lung cancer,” she wrote in a recent legal filing, “I have had mental and emotional distress and inconvenience. I am fearful of death.” She added, “My asbestos-related condition has disrupted my life, limiting me in my everyday activities and interfering with living a normal life.” Asbestos-related? Yes, that’s right. It’s hard these days for smokers to sue tobacco companies because everyone knows the dangers of cigarettes. Instead, McCarthy has become part of a growing trend: lung cancer victims who are suing companies that once used asbestos.

With asbestos litigation well into its fourth decade — the longest-running mass tort in American history — you’d think the plaintiffs’ bar would have run out of asbestos companies to sue. After all, asbestos lawsuits have bankrupted more than 100 companies. Yet McCarthy has found more than 70 additional companies to sue, including General Electric and Pfizer. Asbestos litigation, says Lester Brickman, a professor at Yeshiva University and perhaps the most vocal critic of asbestos lawsuits, “is a constant search for viable defendants.” Because asbestos was once such a ubiquitous product, there is always somebody else to sue.

Let me stipulate right here that exposure to asbestos can be deadly. The worst illness it causes is mesothelioma, a rare form of cancer that essentially suffocates its victims to death. If it were only the real victims of asbestos-related diseases who sued, there would be no issue. That’s how the tort system is supposed to work.

But, over the years, plaintiffs’ lawyers have brought tens of thousands of bogus cases. They took doctors on their payroll to industrial sites, where all the employees would be screened for signs of an asbestos-related disease. They found some real cases, of course — along with many that could never have stood up in court. Nonetheless, by bundling real cases with phony ones — and filing giant lawsuits — they took down one company after another.

The bankrupt company would then put money aside in a trust that would parcel out payments to asbestos victims. The trusts have billions of dollars to disburse and are largely controlled by the plaintiffs’ lawyers. It is a compensation system that runs alongside the tort system.

Eventually, the judiciary got tired of dealing with all the “nonmalignant” cases, as they are called, relegating them to the trusts. At that point, the lawyers mainly handled mesothelioma cases, of which there were some 2,500 a year, and which could generate large payments — usually between $500,000 to $5 million.

But, soon enough, the asbestos lawyers came up with a new tactic: finding lung cancer victims who had some exposure to asbestos. All of a sudden, lung cancer cases exploded in volume. “There is nothing new in the science to suggest an upsurge in cases,” says Peter Kelso, an asbestos expert with Bates White Economic Consulting. “It is just basically due to economic incentives.” That is, by bundling lung cancer cases with other cases, the plaintiffs’ lawyers could bring a new set of companies to heel. For many companies, it is cheaper to settle than fight.

Which brings us back to Congresswoman McCarthy. Her claim for “asbestos exposure” is that when she was young, her father and her brother worked as boiler makers, and she came into contact with asbestos dust because they all lived under the same roof. Plus, she says in her legal filing, she “visited and picked up my father and brother at the various work sites, including Navy Yards, Bridges, Hospitals, Schools, Powerhouses, and other sites where I breathed the asbestos dust.” Her lawyer at Weitz & Luxenberg — which has feasted for decades on asbestos lawsuits — told The New York Post that “it has been conclusively proven that cigarette smoking and asbestos exposure act synergistically to cause lung cancer.” Actually, it hasn’t been: There are plenty of studies saying there is no synergy at all. At best, the science is muddled.

Not that that matters. No doubt McCarthy’s lawsuit will be bundled by her law firm with other cases to force a company that had nothing to do with her disease to pay up. I hope McCarthy wins her battle with lung cancer. It is an awful disease. But the right thing for her to do is drop this lawsuit. All it has really accomplished is showing how asbestos litigation is a giant scam.