Last November, Maui voters through a ballot initiative passed a ban on the cultivation of genetically engineered crops. And now, a federal judge, Susan Mollway, ruled that the ban on genetically modified crops is “invalid and unenforceable” because it is preempted by state and federal law. The county’s ordinance creating the ban exceeded the county’s authority, she said. The county is a major center for research on GM crops due its year-round warm weather.