Two other big tobacco companies are exploring the market. The MarkTen, from Altria, can be recharged; it is being sold in Indiana in a test. The Vuse, from the R. J. Reynolds Tobacco Company, is a long, silver model that is being tried in Colorado.

If those large companies decide to go full force into the market, they could further erode NJOY’s market share, adding a business reason for Mr. Weiss to vilify the tobacco giants. One selling point of NJOY may be its likeness to real cigarettes, but another could be that it was never a tobacco company. He has brought on Mr. Anise and others with tobacco experience, he said, because success depends on relationships with convenience stores that sell cigarettes. But, unlike Mr. Kessler, Mr. Weiss can still rail against the companies that “kill half their customers.”

Mr. Weiss, who turned 40 in July, didn’t come to NJOY as a public health advocate or even as someone whose life was touched by the hazards of smoking. “I have no personal ‘my dad died of lung cancer’ type of story,’ ” he said. Rather, his zeal seems to be equal parts outrage and inborn entrepreneurial excitation. He obtained the first of his three patents at age 15 — it was for a net to catch tennis balls — and went on to become a lawyer before starting a hedge fund.

NJOY was started by Mr. Weiss’s brother, Mark Weiss, a lawyer in Scottsdale, who was inspired by a crude version of an electronic cigar at a trade show in China in 2005. In 2009, the company faced a near-death experience when a shipment from China, where the NJOY cigarettes are made, was seized at the port of Long Beach, Calif. The Food and Drug Administration charged that the e-cigarettes were an unapproved drug-delivery device.

NJOY initially argued that it had made no health claims and therefore shouldn’t be regulated. But just months after the seizure, the Family Smoking Prevention and Tobacco Control Act was passed. It gave the F.D.A. the power to regulate tobacco products, but not to ban them. (At the time, Craig Weiss was a shareholder but not part of management; he did weigh in on legal matters.) After the change in federal law, NJOY updated its legal position, arguing that nicotine is derived from tobacco, and therefore that the F.D.A. had the power to regulate e-cigarettes under the new law. In a 2010 ruling, a federal district court in Washington accepted that argument, preventing an outright ban of NJOY’s product as an unregulated drug delivery device and punting the specifics of how the products should be regulated over to the F.D.A.

The F.D.A. has said it plans to issue preliminary rules for public comment on e-cigarette regulations as soon as the end of this month, but the partial government shutdown appears to have delayed that process. Earlier this month, the European Parliament endorsed limits on sponsorship and advertising of e-cigarettes, and on their sale to minors, but scrapped tougher regulations favored by some in public health that would have regulated them as tightly as medical devices.

Some critics say NJOY and other e-cigarette companies are trying to have it both ways. “When it’s convenient to be like tobacco, they’re like tobacco,” says Stanton A. Glantz, director of the Center for Tobacco Control Research and Education at the University of California, San Francisco, “and when it’s not convenient, they’re not.”