Monsanto has threatened to sue other states over labeling legislation; in 2012, the threat of legal action effectively halted a GMO measure that had been advancing through the Vermont legislature.

Maine will become the second state to require labels on food that contains genetically modified ingredients under new legislation signed by Gov. Paul LePage (R) this week — but only after other states follow suit.

LePage signed the legislation, initially introduced by a Republican state representative, over the objections of agriculture giants who produce many of the raw ingredients that go into everyday foods.

The U.S. Department of Agriculture estimates that about 70 percent of the food products sold in supermarkets contain genetically modified ingredients, the Portland Press-Herald reported.

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