Mandatory GMO labeling is the common sense approach for consumers and our free market economy and is universally supported by Mainers. While Washington prepares to weigh in, we feel it is imperative to remind Sens. Susan Collins and Angus King about the important work that already has been done here in Maine.

Together with our respective parties in the Legislature, we listened to the 90 percent of Mainers who believe they have the right to know whether their food contains GMOs. We fought for Maine’s successful mandatory GMO labeling bill in 2013. This legislation, LD 718, enjoyed the support of a record 123 legislative co-sponsors and passed by virtually unanimous margins, 141-4 in the House and 35-0 in the Senate.

We certainly faced opposition. Monsanto and other industry insiders brought every argument they could think of to Maine to fight GMO labeling. They threatened that labeling would cost them too much money and that these costs would be passed onto consumers. There is absolutely no evidence to support this doomsday prediction. In fact, more than one study indicates food prices will not increase at all when GMO labeling is required. That industry giant Campbell’s Soup has decided to label all its GMO products conclusively proves that labeling is not a hardship for food manufacturers. “Campbell’s has determined that the cost of labeling their products is negligible (and therefore won’t mean higher costs for consumers) and that it’s probably costlier for them not to get out in front of this thing,” Carmen Bain, a professor at Iowa State University who studies GMO labeling, said.

As we so often do, Maine is leading the way on this issue here in the United States, and we’re proud of the work that we’ve done. But we must remind those who argue that the costs of this leadership are too high for our state, that mandatory GMO labeling already is widely used around the world. In the 64 other countries that already require GMO labeling, representing two-thirds of the world’s population, food prices have not increased as a result. These are free market economies with humming industries, high standards of living and affordable food. The only difference between those countries and states such as Maine is that consumers there benefit from labeling transparency and have a real choice whether they want to consume GMOs or not.

In the next few days, the United States Senate will consider dubious industry-backed legislation that would create a questionable “voluntary” labeling system and pre-empt sound mandatory GMO laws passed by overwhelming margins in Maine, Vermont and Connecticut.

The question before Collins and King is not a question of the health or environmental implications of GMOs. Allowing Maine’s GMO labeling legislation to stand will not ban GMOs, increase hardship to farmers or reduce the number of offerings at the grocery store or local market.

The question before Collins and King is whether they will stand with Maine and honor the strong will our state has demonstrated to lead and protect our right to know what is in our food. As it was in Augusta, this issue remains bipartisan with Reps. Chellie Pingree and Bruce Poliquin supporting states’ rights and Maine’s right to legislate our own GMO labeling laws, with both stating they would not support a federal mandate of anything less than what already has passed in Maine.

Monsanto undoubtedly will attempt to buy its way out of any existing labeling requirements with questionable legislation such as the new Senate version of the DARK Act. Monsanto doesn’t want to take the chance that consumers won’t buy as many GMO products if labeling is required or that farmers will choose different farming techniques to meet consumer demand. Monsanto is self-serving and only worried about its bottom line, and that is why this infamous manufacturer of such notorious chemicals as Agent Orange, DDT, PCBs and dioxins is in a full court press to keep voters in the dark.

Maine already has spoken: Personal responsibility dictates that individuals decide for themselves whether they want to buy GMO products. However, this can only be done with information gained from transparency, and that requires mandatory GMO labeling. While other states may choose a different path, we urge Collins and King to respect the work we have done and to stand with Maine citizens on GMO labeling. We urge them to vote against any legislation that would pre-empt Maine’s visionary GMO labeling law.

Former state Rep. Lance Harvell, R-Farmington, and state Sen. Chris Johnson, D-Somerville, were the primary sponsors of Maine’s historic LD 718.