The letter from the Federal Trade Commission to Walgreen Company was good news. After questioning whether the company could substantiate green advertising claims about a line of trash bags sold through its Duane Reade subsidiary, the agency had decided not to pursue an enforcement action. “Among the factors we considered was your client’s decision to promptly stop selling the Apartment 5 Goes Green plastic trash bags in Duane Reade stores,” stated the letter, dated May 18, 2012. “In addition,” the letter continued, “Walgreen assured staff that it will carefully review Duane Reade’s claims and substantiation to ensure that its future advertising complies with the FTC Act.”

Kelley Drye & Warren, which represented Walgreen in the matter, has long analyzed such public closing letters for patterns that explain why the FTC decides to close an investigation. “You can learn a lot by understanding not only the cases that the FTC brings, but the cases that they don’t bring,” says firm partner John Villafranco.