The first time the Food and Drug Administration (FDA) moved to regulate electronic cigarettes, it tried to ban them. Last month it took a different approach that may ultimately have a similar effect. Much will depend on whether the FDA irrationally decides to treat e-cigarettes as a menace to public health or recognizes them as a lifesaving alternative to conventional cigarettes.

On the face of it, the proposed rule that the FDA published on April 22 is much more accommodating than its 2009 attempt to ban e-cigarettes as unapproved "drug-device combination products," which was blocked by the courts. This time the FDA is classifying e-cigarettes as "tobacco products." That in itself is rather puzzling, since e-cigarettes do not contain any tobacco. They do, however, contain nicotine derived from tobacco, which is the court-endorsed legal pretext for FDA regulation.

By the same logic, nicotine gum, lozenges, patches, and inhalers are also tobacco products, except that the FDA already regulates them as pharmaceuticals. As tobacco products, e-cigarettes should have a much better chance of remaining on the market. After all, the FDA is not trying to ban conventional cigarettes, which are far more dangerous because they deliver nicotine in a cloud of tobacco combustion products rather than a propylene glycol aerosol.

But there's a catch. All the familiar brands of conventional cigarettes were grandfathered by the Family Smoking Prevention and Tobacco Control Act, the 2009 law that gave the FDA authority over tobacco products. According to the FDA, so were e-cigarettes, as long as they were on the market as of February 15, 2007—the cutoff date set by the statute. Since the e-cigarette business was just getting started in the United States at that point, this grandfather clause does not cover much.

E-cigarette companies that did not exist in early 2007 can get permission to continue selling their products by demonstrating that they are "substantially equivalent" to the early models, which means they have "the same characteristics" or raise the same public health issues. Will they be able to meet this test? I asked three people who are familiar with the e-cigarette industry that question, and I got three different answers.

The most optimistic answer came from Chip Paul, founder of the Oklahoma-based e-cigarette franchise Palm Beach Vapors, which sells vaping equipment and store-blended fluids to go with them. "I think everybody will be able to make that argument, that they are just furthering the technology that existed in 2007," Paul says. One major change has been the shift from disposable cartridges of e-cigarette fluid to refillable tanks, but the underlying technology remains the same. "We don't think what's on the market today is substantially different from what was on the market in 2007," Paul says. "There have been improvements in the technology, and there have been some design changes, but the way the liquid is delivered to the user is fundamentally the same, and the liquid is fundamentally the same. I think everybody who is in business today will be able to [satisfy that test] and be OK."

Oliver Kershaw, founder and CEO of E-Cigarette Forum, is much less sanguine. "Most vaping products now being used will not qualify," Kershaw said in an emailed statement last week, "and will have to be submitted as new products, with huge expense incurred….This is a highly costly and lengthy process [that] will create an unnecessary barrier to entry that will remove the vast majority of the products vapers are currently using to stay off tobacco. It's a de facto ban that makes every other potentially positive concession in the proposal irrelevant."

Kershaw tells me he is especially concerned about smaller companies offering refillable vaping equipment that does not use cartridges and does not look like a cigarette. He worries that they won't have the resources to deal with the FDA's demands. "For this particular category, there's no indication of what substantial equivalence is," he says. But judging from substantial equivalence applications for other tobacco products, "the level of detail required is phenomenal," and the process can drag on for years. Of the more than 3,000 substantial equivalence applications the FDA has received since 2009, Kershaw notes, only 20 to 30 have been approved so far.

Jason Healy, founder and president of Blu eCigs, agrees that most current products—"99.9 percent," he says—won't qualify as "substantially equivalent," but he sees signs of flexibility at the FDA. "For some products," the agency says in its proposed rule, "there may not be predicate products that were on the market as of February 15, 2007, to which to claim substantial equivalence. This may be particularly true for e-cigarettes and similar novel products….FDA is specifically seeking comment on whether and, if so, how FDA should consider a different regulatory mechanism for newer proposed deemed tobacco products that cannot, as a practical matter, use the SE [substantial equivalence] pathway."

Healy sees such statements as evidence that the FDA wants to find a way to keep e-cigarettes on the market. "The FDA is saying they understand that mechanism won't work for e-cigs, so they're looking to make a system that will work to approve new products," Healy says. "I don't have any concerns that [the cutoff date for substantial equivalence] will cause any problems. It's just a question of how they work around it."

To win approval of an e-cigarette as a "new tobacco product," a company has to persuade the FDA that "permitting such tobacco product to be marketed would be appropriate for the protection of the public health." Here the agency's view of e-cigarettes' harm-reducing potential will be crucial. In its rule the FDA acknowledges the argument that e-cigarettes can reduce tobacco-related disease by providing a less hazardous alternative to smoking but says "we do not currently have sufficient data about e-cigarettes and similar products to determine what effects they have on the public health."

The answer, the FDA says, hinges partly on e-cigarettes' effectivenessas a smoking cessation aid. But as Boston University public health professor Michael Siegel points out, the agency also suggests it's not clear whether switching from smoking to vaping reduces health risks. "Many consumers believe that e-cigarettes are 'safe' tobacco products or are 'safer' than cigarettes," it says. "FDA has not made such a determination and conclusive research is not available." Siegel, who views e-cigarettes as an important harm reduction tool, notes similar statements in a recent Tobacco Control article by Priscilla Callahan-Lyon, who works in the Office of Science at the FDA's Center for Tobacco Products. "While e-cigarette aerosol may contain fewer toxicants than cigarette smoke," Callahan-Lyon writes, "studies evaluating whether e-cigarettes are less harmful than cigarettes are inconclusive."

Such seemingly cautious statements are in fact reckless, because they discourage smokers from making a switch that could literally save their lives. It is beyond serious dispute that the aerosol generated by e-cigarettes—which consists mainly of propylene glycol, an FDA-approved food ingredient, plus nicotine and flavoring—is much less hazardous than the myriad toxins and carcinogens in tobacco smoke. The fact that the FDA remains unconvinced on this point does not bode well for its receptiveness to letting e-cigarettes stay on the market.

It could be years before the FDA's true intentions become clear. Once the proposed rule is finalized, which might take a year or so, e-cigarette companies will have two years to apply for approval of their products. How long it will take the FDA to act on those applications is anybody's guess, and litigation challenging aspects of the regulations could delay the process further. In the meantime, the FDA says, applicants can continue to sell their products.

Assuming that Jason Healy is right and the FDA finds a way to approve e-cigarettes, that does not mean it will let companies tell the truth about them. In the FDA's view, any statement about the relative hazards of e-cigarettes transforms them into "modified risk tobacco products," which are legal only if the FDA decides they "will benefit the health of the population as a whole." To meet that test, it would not be enough to demonstrate that e-cigarettes are safer than the conventional kind. The inquiry also would entail predicting the net impact of e-cigarettes on smoking rates, taking into account implausible fears that vaping might lead to smoking or prolong the habit in people who otherwise would have quit. It is not clear what sort of evidence would satisfy the FDA on that score, but it would not be cheap or easy to obtain.

To avoid that burden and keep their products legal, e-cigarette companies will have to eschew any statements, no matter how accurate, that the FDA might interpret as implying a health advantage. "An electronic cigarette company cannot even inform consumers that the product does not produce smoke," writes Siegel, "because such a claim would be considered a 'reduced exposure' claim." Likewise claims that e-cigarettes do not contain tobacco or do not generate "tar." For companies dealing with the FDA's censors, truth is no defense.

Healy, whose company has been criticized for ads featuring bikini-clad women, argues that the FDA's suppression of truthful, nonmisleading information forces e-cigarette companies to rely on sex and glamour to sell their products. "If people want to say the advertising is glamorizing smoking," he says, "that's only happening because of the absence of claims. If you can't make a claim, you really have no choice but to use sex and sexy advertising."

Kershaw complains that the FDA has created an "absurd situation in which manufacturers will not be allowed to claim what is unanimously accepted as the truth: that vaping products are safer than smoking tobacco. What is desperately needed to combat the harms of tobacco smoking is for smokers to be informed that noncombusted tobacco products, including vaping, are known to be orders of magnitude safer than inhaling burned plant material."

This article originally appeared at Forbes.