After deliberating one day, jurors returned not guilty verdicts in the W.R. Grace & Co. trial, ruling in favor of the company and three individual defendants, reports The Missoulian in Missoula, Montana. Grace and three former employees were charged with a federal conspiracy involving Clean Air Act violations and obstruction of justice. The charges relate to whether the company and its top employees knew they were endangering the community of Libby by mining asbestos-laced ore, and whether they did so in violation of federal law. The jury of six men and six women had the task of determining whether the evidence proves that Grace's alleged criminal conduct occurred within an applicable time frame. The criminal provision to the Clean Air Act, which charges knowing endangerment, wasn't enacted until 1990, the same year the Libby mine ceased operations.