A federal judge in Delaware says a legal battle between the Dupont Co. and Vermont officials over genetically modified foods should play out in Vermont. The judge on Friday granted a request by Vermont officials to transfer the case to their state, where trade groups representing food producers are fighting a new law requiring the labeling of foods containing genetically modified ingredients. The first-in-the-nation law is to take effect July 1. The Grocery Manufacturer's Association is leading a court challenge claiming, among other things, that the labeling law violates the First Amendment and is unconstitutionally vague. Meanwhile, Dupont and Syngenta Corp. are fighting efforts by Vermont officials to force the companies to turn over results of their research regarding the potential health and environmental impacts of genetically engineered crops.