With Governor Peter Shumlin's signature on May 8, Vermont became the first state in the country to require foods made with genetically modified ingredients (GMOs, for genetically modified organisms) to carry a label -- although the effective date is July 1, 2016, and that depends on defeating legal and constitutional challenges.

In this case, there was no ballot initiative, as those that failed narrowly in California in 2012 and Washington state in 2013. The Vermont bill wound its way through the state's legislature since January 2013 and was approved in its final form by the two legislatures on April 23.

What's next? Either a raft of litigation challenging the law or a pre-emptive strike with a national labeling law, perhaps overseen by FDA, which, while not turning back the clock at least would prevent 50 potentially different state laws from making interstate commerce impossible.

The Grocery Manufacturers Assn. called it "a bill that is critically flawed and not in the best interests of consumers. It sets the nation on a costly and misguided path toward a 50-state patchwork of GMO labeling policies that will do nothing to advance the safety of consumers.

“GM crops are safe and have important benefits for people and our planet," the GMA statement continued. "They use less water and fewer pesticides, reduce crop prices by 15-30 percent and can help us feed a growing global population of seven billion people. The FDA, World Health Organization, American Medical Assn. and U.S. National Academy of Science have all found that foods and beverages that contain GM ingredients are safe and materially no different than conventionally produced products."

Sensing the rising tide, GMA has thrown its support behind bipartisan federal legislation, the Safe and Accurate Food Labeling Act, HR 4432, which "would require a label on foods containing GM ingredients if the FDA – our nation’s foremost food safety authority – determines there is a health or safety risk. Any labeling of GM ingredients would therefore be based on science, not fear or the varying politics of the 50 states."

The Burlington (Vt.) Free Press, quoting the National Conference of State Legislatures, reported there are 84 bills on GMO labeling pending in 29 states, as well as bills in Congress. The Free Press also reported that earlier this year, Maine and Connecticut passed labeling requirements contingent on a “trigger” mechanism: The requirements won’t take effect unless several neighboring states take the same step. And ballot initiatives are being pushed this year in Oregon, Colorado and Arizona.

The new Vermont law offers three wording options subject to modifications by the Vermont attorney general's office: "partially produced with genetic engineering," "may be produced with genetic engineering," or "produced with genetic engineering."

There are many exemptions, including liquor, meat and dairy products and  food served in restaurants and institutions. Meat is regulated by the federal government. Authors of the bill argue that dairy products made from animals that eat genetically modified food are not themselves genetically modified. Liquor is not considered food. Restaurants are exempt because authors of the bill said they were focusing on foods where consumers routinely see labels.

Also, no food that contains GMOs may be labeled natural, at least after the law takes effect.