Over the weekend, California residents bid au revoir to foie gras, as a statewide ban signed in 2004 finally took effect on Sunday. The expensive delicacy is made from the livers of geese or ducks which have been fattened, often through a controversial force-feeding system called gavage. The Force Fed Birds Act of 2004 (text via CA legislature or HeinOnline’s Session Laws Library) prohibits both the practice of gavage as well as the sale of products which result from such force feeding, meaning that California farmers and restaurateurs alike are affected by the ban.
Most new laws don’t take effect immediately, in order to allow sufficient time to adjust to changes. In fact, California usually delays the effective date of new laws until the following January 1 (see Gov. Code § 9600 at http://leginfo.legislature.ca.gov/faces/codes.xhtml). But if a 7+ year delay seems excessive, look no further than the statute itself for the explanation: the lengthy gap was intended to give those "engaged in agricultural practices that include raising and selling force fed birds" a fair chance "to modify their business practices" in the meantime. (It also gave California diners a chance to do some gorging of their own, and the L.A. Times reports that diners took full advantage.)
California wasn’t the first, or only, place to ban the production or sale of foie gras. Several European countries have ceased production of foie gras since the late 1990s, although most do not also prohibit its import or sale. Closer to home, chapter 2 of the recent ABA publication The Little Book of Foodie Law details the City of Chicago's 2006 attempt to ban the sale of foie gras in its stores and restaurants. (The unpopular and poorly-enforced prohibition was repealed in 2008.) Other chapters describe interesting cases concerning other food-related laws, including trademark infringement suits, squabbles over the C.F.R. definitions of "olive oil" and "cream cheese," and tort claims against a wedding caterer for serving non-kosher food at a Jewish couple's wedding. As an added bonus, each chapter contains a recipe related to the topic. (California residents won't have much luck with the foie gras chapter, as it calls for the now-banned product: perhaps they can substitute the New York Times’ instructions for "faux gras" made with chicken livers.)
To learn more about laws and regulations which impact the food you eat, try a subject search of the Duke Libraries Catalog for "Food Law and Legislation" or Ask a Librarian.