Talking about GMOs can sometimes feel like two people playing chess who don’t agree on what a pawn does or how a queen can move. There’s so little agreement on even the most basic terms that it’s hard to start a dialogue.

For example, not everyone agrees on what a genetically modified organism actually is, or even that we should be calling them GMOs. Some people prefer the term GE for genetically engineered, others think “bioengineered” is the way to go.

So, why are these semantic distinctions important? Because Congress just passed a law that requires food makers to inform shoppers whether their products contain GMO ingredients. Without a basic understanding of what a GMO is, it’s going to be difficult for these companies to comply with the law.

Environmental attorney Keith Matthews, with the law firm Sidley Austin LLP, is trying to help these food companies sort all of this out. Before going to Sidley, Matthews headed up the division at the Environmental Protection Agency that regulated pesticides in GMO crops.

We spoke to Matthews for the latest episode of our biweekly podcast, Parts Per Billion. He explained to us why Congress attempted to define in its law what a GMO is, and what the implications are of the definition the lawmakers ultimately came up with.

He also pointed out that the law’s vagueness in many areas actually represents a broad grant of authority to the executive branch—specifically to the U.S. Department of Agriculture.

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