The difficulty of testing for marijuana intoxication and the complexity of Maine’s drug-testing laws are creating uncertainty among state officials and employers about the workplace impacts of a legal marijuana market.

“It’s uncharted territory to a great extent,” said Julie Rabinowitz, director of policy, operations and communications for the Maine Department of Labor.

All employees at Volk Packaging Corp. in Biddeford must pass pre-employment drug screening. State officials have sought guidance from Colorado about how a recreational marijuana market could affect employers that drug-test employees or maintain drug-free workplace policies. Shawn Patrick Ouellette/Staff Photographer Derek Volk, president of Volk Packaging in Biddeford, says he doesn't expect the company to alter its drug-testing policy. "We're trying to learn what the law exactly would say and what our abilities would be based on someone failing a drug test," he said. "I don't know how we determine a potential employee's opportunity here if...