In an action challenging a ballot initiative ordinance banning the cultivation and testing of genetically engineered (GE) plants, the District Court's grant of summary judgment to defendants is affirmed where: 1) the ordinance is expressly preempted by the Plant Protection Act, 7 U.S.C. section 7756(b), to the extent that it bans GE plants that the U.S. Animal and Plant Health Inspection Service (APHIS) regulates as plant pests; and 2) the ban is not impliedly preempted by the Plant Protection Act in its application to GE crops that APHIS has deregulated, but is impliedly preempted in this application by Hawaii's comprehensive state statutory scheme for the regulation of potentially harmful plants.