In the United States, pre-packaged foods loaded with artificial ingredients and chemicals can make it onto grocery store shelves boasting the label "natural."
Why? Because in America, there is no definition of "natural."
This gray area has led consumer advocates to threaten lawsuit after lawsuit against big food giants, alleging that their claims are misleading and illegal.
"It only scratches the surfaces of the number of companies that are making these claims. We keep coming across them," he said.
Some lawsuits have been merely threatened by CSPI, and eventually settled out of court after the company agreed to change labeling.
Others have been filed by private parties seeking class action payouts.
The latest involves Kraft Foods, maker of Crystal Light powdered drink mixes which contain artificial sweeteners and colors, a texturizer called maltodextrin and a synthetic preservative called butylated hydroxyanisole.
In January, CSPI notified Kraft of its intent to sue if the word "natural" continues to appear on products like Natural Lemonade and Natural Lemon Iced Tea.
Gardner said talks with the company are ongoing, but given his experience -- he first sued Kraft over similar claims on its Capri Sun drinks in 2007 -- he expects Kraft to counter that the word "natural" relates to the flavor.
"I am not aware of a lemonade flavor. I am aware of lemon," Gardner said.
Asked for comment, a Kraft spokeswoman told AFP that a federal judge in California recently dismissed a similar claim against Crystal Light.
"Our products are clearly and accurately labeled with information that is both truthful and helpful for consumers," spokeswoman Caroline Krajewski said in an email.
Foods that claim to be "natural" but clearly are not can slip past authorities because the main U.S. regulatory agency, the Food and Drug Administration, has not formally defined "natural."
However, the regulator has sent several warning letters to companies in the past, FDA spokeswoman Theresa Eisenman told AFP in an email.
"Although the FDA has not established a formal definition for the term 'natural,' we do have a longstanding policy concerning the use of 'natural' in food labeling," she said.
"The FDA considers the term 'natural' to mean that nothing artificial or synthetic (including all color additives regardless of source) has been included in, or has been added to, a food that would not normally be expected to be in the food."
The FDA has left Crystal Light alone, and consumer groups complain that regulators are not aggressive enough, leaving plenty of room for corporations to exploit well-meaning shoppers who appear to be susceptible to packaging claims.
According to the market research firm Nielsen, "natural" products produce over $22 billion in annual sales.
A full 77 percent of US consumers polled said they believe "natural" claims at least some of the time, and nine percent said they always do.
Despite the high volume of lawsuits, the matters often settle out of court and corporations avoid big payouts, said Gardner.
"We stop them, but they get to keep the money they stole from consumers by fraud," he said.
In some cases, a company relents to pressure from consumer groups but is sued again by private interests seeking a cash payout to people who bought the product.
Such was the case with Ben and Jerry's ice cream, which took the claim off 48 products in 2010 but has since faced a drawn out class-action lawsuit.
Some companies have quietly dropped "natural" from their packages, including Naked Juice and Frito Lay chips, as the food industry faces thorny legal questions over genetically modified ingredients and common additives like corn syrup.
In Gardner's view, the lawsuits would stop if the FDA came up with a definition for "natural."
But Baylen Linnekin, executive director of the non-profit group Keep Food Legal, said more regulation is not the answer.
"The idea that the FDA needs to define every word that has ever been used to refer to food is ludicrous," said Linnekin. "The occasional lawsuit helps keep companies honest and that has always been the case."
ALERT: Frankenfoods, Protect Yourself From the Hidden Dangers Now