BURLINGTON, Vt.—The Grocery Manufacturers Association (GMA) and three other trade groups have sued Vermont to block the first GMO food labeling law from taking effect.

In a complaint filed Thursday in the U.S. District Court for the District of Vermont, the plaintiffs argued Act 120 violated the First Amendment and a number of other provisions of the U.S. Constitution.

Effective July 1, 2016, the law requires food manufacturers to label foods produced through genetic engineering.

The trade groups claimed Act 120 will severely burden the food industry because most foods at grocery stores contain genetically modified organisms (GMOs). Plaintiffs argued Vermont failed to calculate the benefits and costs of the measure or consider less burdensome alternatives; and the lawsuit characterized the labeling deadline as “difficult, if not impossible" for many of plaintiffs’ members.

“They must revise hundreds of thousands of product packages, from the small to the super-sized," wrote lawyer Matthew Byrne of Burlington, Vt.-based Gravel & Shea PC on behalf of the plaintiffs. “Then, they must establish Vermont-only distribution channels to ensure that the speech Vermont is forcing them to say, or not say, is conveyed in that State. To comply by the deadline, some companies may have no choice but to revise the labels for all of their products, no matter where they might be sold in the United States."

The lawsuit didn’t come as a surprise to the state Attorney General William Sorrell, who earlier predicted legal challenges and has promised to “mount a vigorous and zealous defense of the law."

Unlike GMO labeling laws in Connecticut and Maine, Vermont’s law doesn’t require passage of similar laws by other states in order to take effect.

Last month, Vermont Gov. Peter Shumlin said more than 60 countries already restrict or label GMO foods. But the trade groups challenging Vermont’s law noted FDA doesn’t require GMO labels and has verified “the safety of more than 100 genetically engineered crops for human consumption" since 1994.

In the complaint, plaintiffs argued Vermont doesn’t have a sufficient government interest to compel the labels, running afoul of the protections commercial speech is afforded under the First Amendment.

“The State’s unwillingness to use its own funds to administer and defend Act 120 is express confirmation that Vermont does not have a ‘state’ interest in the survival of this law," plaintiffs declared through their attorney. “Act 120 thus fails any standard of First Amendment scrutiny."

The lawsuit further alleged violations of the 5th, 14 and 15th Amendments as well as the Commerce and Supremacy clauses. The complaint also argued the law is preempted by a number of federal laws, including the Nutrition Labeling and Education Act.

Plaintiffs in the lawsuit include GMA, whose members generate more than USD $460 billion in annual sales, plus the Snack Food Association, International Dairy Foods Association and National Association of Manufacturers.