It was May 8, 2014, when the state of Vermont—knowingly or not—launched the war with the American food industry that spilled onto the floor of the U.S. Senate yesterday.

Sitting behind an antique desk brought onto the steps of the statehouse in Montpelier for the occasion, Gov. Peter Shumlin signed a bill that would make Vermont the first state to require the labeling of genetically modified organisms, or GMOs. Vermont is a heavily agricultural state that prides itself on a reputation for purity: green mountains, real maple syrup, small dairy farms. And though bioengineered foods don’t pose any documented health risk, its legislature had decided, by a large majority, to stand firmly on the side of caution.

“Vermonters take our food and how it is produced seriously, and we believe we have a right to know what’s in the food we buy,” Shumlin, a Democrat, told the crowd of hundreds watching from the lawn in front of the building. “I am proud that we’re leading the way in the United States to require labeling of genetically engineered food.” Much of the crowd that day was enjoying free scoops of ice cream from Ben and Jerry’s, a local company that had supported the law.

Requiring the labeling of GMO foods seems like precisely the type of thing that would start in Vermont, and just as likely stay there. With just 600,000 people, Vermont is known for idiosyncratic positions: It bans roadside billboards, elected a socialist as mayor of its largest city, and ruthlessly polices use of the word “maple” in any food that does not contain actual products of the maple tree.

But to the food industry, this was no minor gesture from an obscure left-wing state. It represented a threat to the entire American food system. What has worried its opponents since the moment states began seriously considering labeling laws in 2013 is that the system is too complex—and GMO corn, soy and sugar too deeply threaded into the American food supply—for a state restriction to end at a state’s borders. If the law in Vermont is allowed to go into effect, the industry warns, there will be chaos.

Large food companies and farming lobbyists swung into action, and Republicans in Congress spent the winter garnering support for a law that would pre-empt all state GMO labeling laws. Their hope was to set a standard for GMO labeling that states couldn’t exceed—and which would be voluntary, not required. In theory its supporters called the bill precautionary; in practice it would have had one immediate effect: stopping Vermont.

Yesterday the bill came to the Senate floor, and the winner was Vermont. Its supporters mustered only 48 votes to limit debate—far short of the 60 they needed to move it through the Senate. Unless a compromise emerges in the next few months, or a judge steps in, as of July 1, 2016, a national precedent will effectively have been set on that May morning in northern New England—not just on GMOs, but potentially on any type of politically sensitive ingredients. And no one is quite sure where it will end.

POLITICALLY, GMOs HAVE hit the front burner this year, with the labeling bill on Capitol Hill and a parallel debate about how to legally market GM salmon, the first genetically engineered animal approved for human consumption. But scientifically, the issue is old news: The technology to genetically alter plants is more than three decades old. While the technology can, in theory, be used to change a whole host of attributes—improving flavor, nutrition value, durability—it has been used almost entirely on pesticide resistance for big commodity crops. In 1996, agribusiness giant Monsanto introduced its first variety of pesticide-resistant GMO corn, and now more than 90 percent of corn, soy and sugar beets grown in the United States are genetically modified.

Governments and groups such as the World Health Organization have declared that consuming GMO plants is safe for humans. But labeling, opponents of GMOs say, isn’t so much a health warning as a matter of letting consumers choose whether they want to support the production system such foods represent. They worry that it’s opening the door to a new future of unmeasured long-term risks to health, the environment and other plant genomes; they point out it is already reducing crop diversity and leading to massive increases in the use of the pesticide glyphosate. Biotechnology companies counter that GE crops have increased yield and reduced the use of pesticides. The technology is necessary, they say, to feed an ever-growing population without plowing up more land for farms.

So far, more than 60 countries—including all of the European Union, Russia and Brazil—have restricted or labeled these foods. In the U.S., “GMO free” has become a kind of clean-branding mechanism; more than 27,000 products have been certified by an independent group called the Non-GMO Project; even mainstream brands like Chipotle are swapping out GMO ingredients. But, so far, food-makers have managed to keep the government out.

Enter Vermont. The state is particularly proud of its local food movement, boasting more farmers’ markets and certified organic farms per capita than any other, and it already has a long history of tackling GMOs. In 1994, Vermont passed a law requiring the labeling of a genetically engineered protein, known as rBST, that was aimed at boosting milk production in cows. But the law didn’t last: A federal court two years later found that the labeling law violated the dairy industry’s First Amendment rights. Legislation on labeling and seed purity continued to come up in Montpelier over the following years, though with few successes.

Then other states began to test the same waters. In 2012, a GMO labeling law was put in front of voters in California in a ballot initiative. Large food and agriculture companies, including Coca-Cola, PepsiCo and Monsanto, spent more than $45 million to defeat it. The measure failed by less than 3 percent, and the effort encouraged other states to do the same. The following year, legislatures in Connecticut and Maine passed GMO labeling laws, though both contain trigger provisions preventing them from them taking effect until a number of other states put in place similar measures.

Vermont’s law was next—but it didn’t contain any triggers. It was very clear: On July 1, 2016, all products on grocery store shelves containing GMOs must be labeled, or food companies will be subject to fines. The law includes exemptions for dairy, meat and certain other products.

A month after the law was signed, the state was sued by the Grocery Manufacturers Association, the food-industry trade group that had been leading the charge against state labeling efforts. The suit argued that the law violates its First Amendment rights and interferes with interstate commerce, and pushed the court to stop the measure from taking effect. A federal district court rejected the industry’s request for an injunction, and a ruling on an appeal is still pending.

Meanwhile, companies and farm groups took their concerns to Capitol Hill and were successful, in July 2015, in getting a bill passed in the House. The bill reads like an industry wish list: In addition to pre-empting states, it required the Agriculture Department to set up a voluntary GMO-free certification and defines the word “natural,” when used on food labels, to include GMOs. It was never taken up by the Senate.

WHY SO MUCH attention to Vermont? The problem with Vermont’s law, the food industry argues, is that it’s not really just a Vermont law. The American food distribution system isn’t designed to accommodate different labels for different states, instead relying on the U.S. Food and Drug Administration to give companies clear guidance on what they do and don’t need to tell consumers. America’s national food producers, like drug companies and other closely regulated consumer industries, expect to deal with one major regulator—the federal government—and only worry about one set of standards. Even if they were open to marketing its food under multiple labels, officials from Coca-Cola, General Mills, PepsiCo and others argued in legal briefs, the complicated regional supply chain—from factory, to distribution centers, to supermarket shelves—makes it nearly impossible to craft a new label for a single state. The Vermont label would end up elsewhere; mislabeled foods could easily end up in Vermont, accidentally violating the law. So food companies are left with the choice of a costly overhaul of their supply networks, or of applying the new label to all of their products—effectively meaning that Vermont’s law would become the national standard.

It might sound extreme to suggest that a tiny New England state is setting a de facto food-labeling policy for the rest of the country. But something similar has already happened with egg production. In 2008, California voters passed a ballot initiative that called for the hens producing eggs sold in the state to be “cage free.” Producers and other states pushed back against the rules initially, asking a federal court to block the measure, which it declined to do, and threatening massive increases in egg prices once the rule took effect at the beginning of 2015. But the change has stuck. Now consumers and, increasingly, restaurants are calling for eggs that effectively meet California’s standard. Without any rules from Washington, the movement to “cage-free” is currently one of the fastest-moving waves in the food system.

It helped, of course, that California has the largest market in the country. And while California challenged an animal welfare issue for a single commodity, with GMO labeling, the food industry is worried that lawmakers in Montpelier have opened a far larger Pandora’s box: If Vermont can decide to force GMO labeling, any state could decide to require any attribute of food to be disclosed on the outside of every package of food.

The industry also points out that there is a reason GMOs currently are not labeled. The FDA requires labeling only if something—such as allergens or calories—poses a health or safety risk. GMOs have been deemed safe by the federal government. But if Vermont’s law stands, it would clear the way for other states to put in place their own, potentially different, GMO labeling standards—or pick on other attributes of food and food processing based almost entirely on consumer curiosity. So if Nebraskans suddenly became concerned about whether the chocolate in products is sustainably produced, for example, the food industry could be burdened with another state-specific label. Or if Floridians started worrying about irradiation used on spices and vegetables, that could be another label.

“We know that we have to stop the wrecking ball,” Sen. Pat Roberts (R-Kan.), the bill’s sponsor, told reporters recently. “That’s the whole thing.”

THEY DID NOT, in fact, stop it. Though Republicans largely signed on, the food industry couldn’t bring over enough farm-state Democrats to get the 60 votes it needed. For now, the bill is effectively dead.

This isn’t just a Republican worry: Even Tom Vilsack, President Barack Obama’s secretary of Agriculture, has said that Congress needs to pass some kind of GMO rule—even if it’s voluntary, or doesn’t go on the label—to avoid the confusion that will set in when states begin making their own.

That confusion now seems inevitable. Other states—most notably, Massachusetts—are close to passing their own GMO labeling laws, and lawmakers in Connecticut are trying to remove the trigger provision in that state’s law, which requires them to wait until enough nearby states enact similar legislation. Lawmakers in Maine are also looking to ease their law’s trigger requirement and enact GMO labeling sooner.

One party that won’t be surprised: food-makers themselves. Even as their Senate allies fought the bill, they’ve been preparing to label their products to meet the Vermont standard. Last fall, the state’s attorney general released details on what the labels must look like, and as recently as last month, he offered more clarifications to help companies know what will be expected of them. Changing a product’s label takes about 10 months from design to getting the packaging on the shelf, an official from Coca-Cola told the court in Vermont, so food companies needed a long runway. Now, with just four months to go, somewhere at almost every big food company that wants to keep its products in Northeastern stores, there is likely a can of soda, box of cereal or package of cookies preparing to go into mass production that in a small font near the nutrition facts panel, says, as Vermont asks them to: “produced with genetic engineering.”