At the end of last summer, I explored, in the pages of The Nation’s special food issue, the complex implications of Wal-Mart’s move to expand its organic offerings. (Sorry, only the first couple paragraphs are online.) Like most of my writing about the environmental implications of Wal-Mart’s policies, the article was balanced. Although I believe Wal-Mart is bad news for American workers, and has made almost no meaningful attempt to reform its personnel practices, I do think that some of the company’s “green” reforms have the potential to genuinely help the earth.

Well, the jury’s still out on the company’s broader environmental impact, but on organics, it looks like I may have been too kind to Wal-Mart. The Cornucopia Institute, a watchdog group that advocates for family-scale farms and has been following Wal-Mart’s organic moves with rigorous skepticism, discovered four months ago that Wal-Mart has been mislabeling non-organic products as organic. Though Cornucopia informed Wal-Mart about the problem, and filed a formal complaintwith the United States Department of Agriculture, many of the inaccurate signs remain .

Earlier this month, Corncopia filed a consumer fraud complaint with the Wisconsin Department of Agriculture, Trade and Consumer Protection. Today, Wal-Mart Watch put out a call for action: Write or email USDA honcho Eileen Broomell and urgeher to begin a nationwide investigation of Wal-Mart’s product labeling.

Fraud of this kind is a serious matter, especially with more and more companies marketing social responsibility. According to a study released last week by the marketing firm Packaged Facts, U.S. sales of grocery store products making an ethical claim – organically grown, hormone-free, eco-friendly, local, cruelty-free – have skyrocketed in the past year, reaching nearly $33 billion in 2006, up 17% from 2005. Packaged Facts projects that sales of such items will continue to grow, surpassing $57 billion in 2011. People relish the opportunity to make a difference at the cash register; sure, that impulse may sometimes be naive, but companies like Wal-Mart shouldn’t get away with abusing customers’ good intentions.