By Matthew Power. In Ohio, thousands of unionized trade contractors will soon carry cards stating that they have tested free of drugs. The brainchild of an alliance of contractors, unions, and energy companies, the program aims to improve the current situation, where workers must face re-testing for drugs each time they move to a new jobsite. Under the ID card plan, workers are tested once each year for various drugs, and a quarter of participants are subject to random testing during the year.