It’s last-minute Congressional budget season, which, for politicians, means it’s time to sneak totally unrelated provisions into the budget bill. And this year, the Republicans have a gift for all the vapers out there: a provision about the “grandfather date” for tobacco products. Wait, what? But keep reading—this obscure little provision could exempt current e-cigarettes from upcoming regulation, all by going around the Food and Drug Administration.

Whatever you think of e-cigarettes, the FDA clearly wants to start regulating them. E-cigarette use has risen dramatically, and most worrisome for public health advocates, teen use tripled from 2013 to 2014. The FDA has not revealed its final e-cig rule yet, but the vaping industry fears the worst. “It will decimate all but a small handful of manufacturers,” says Gregory Conley, president of the American Vaping Association, an industry-funded advocacy group. To prevent that, they’ve focused on the grandfather date.

The FDA gets the power to oversee tobacco products—like cigarettes and chewing tobacco—from the Tobacco Control Act. Congress passed it in 2009, but the act grandfathers in tobacco products that were on the market before February 15, 2007, so their manufacturers don’t need FDA review of those products. E-cigarettes are such a new category that the FDA doesn’t have a rule deeming them a tobacco product yet, and also, uh, e-cigarettes didn’t exist in the US before 2007.

E-cigarettes became popular a couple years later, and in that unregulated market bloomed hundreds of flavors like Unicorn Puke and Fruit Squirts, often marketed to teens. Under the Tobacco Control Act, manufacturers of new tobacco products—including basically every e-cig maker, if the FDA gets their way—have to file a “retroactive premarket application,” which is a great piece of bureaucratic language, to continue selling their products. The FDA reviews the product’s ingredients, packaging, and health risks.

But push the grandfather date forward, as the vaping industry hopes Congress will do, and e-cig makers get grandfathered along with all the old cigarettes and chewing tobacco—so no FDA review needed. That’s good for business. On the other hand, if teen vaping is your concern, the American Lung Association’s head of advocacy, Erika Sward, says pushing the grandfather date “essentially opens the door for years to come for these candy and fruit-flavored products.”

The vaping industry has fought regulations since 2009, when the FDA seized e-cigarette shipments as unapproved drug delivery devices. Tobacco companies sued the FDA, and a judge ruled the agency could only regulate e-cigarettes as tobacco products, which could require a less stringent review. The FDA released a draft rule to regulate e-cigs in 2014, and in October it sent a final rule to the White House, which has 90 days to approve or kick it back to the FDA.

The argument for lighter, or no, regulation is that e-cigarettes are safer than traditional cigarettes, which nearly everyone agrees with. But what’s better for you individually may not translate to what’s better for society as a whole. Here is where the evidence gets murkier. Are heavy smokers switching to e-cigarettes, which is a net positive? Or are people who would otherwise quit or never start using tobacco now vaping, a net negative? Do these two effects cancel each other out? Not enough solid research exists to support any argument, but public health advocates have reason to err on the side of caution: “There’s no such thing as a safe addictive product,” says Gregg Haifley, federal relations director of the American Cancer Society Cancer Action Network.

The Tobacco Control Act does, in fact, have a regulatory pathway to prove a product comes with “reduced harm.” It comes out of tobacco companies marketing their products as “light” or “low” without any scientific proof to back it up. So far, only one company, Swedish Match, has tried with snus (a type of loose tobacco that comes in teabag-like pouches). The FDA's advisory panel was split on whether Swedish Match can drop warning labels on its snus, and an official decision is still pending1. Swedish Match submitted thousands of pages of documents for the process, and Conley says it would be prohibitively expensive for small manufacturers.

Both sides agree, however, that the FDA should set standards to keep out harmful chemicals, like diacetyl, a chemical that causes a respiratory condition called “popcorn lung.” A report from Harvard researchers this week found diacetyl in 75 percent of tested e-cigarettes. But the FDA can’t set product standards for e-cigs until they’re officially classified as tobacco products, which comes with the premarket application requirements. Unless, of course, Congress decides to grandfather in e-cigs. It’s bureaucratic wrangling all the way down.

1 UPDATE 12/14/15 12:50 ET: This story has been corrected to accurately reflect the status of Swedish Match's modified risk application for snus.