State lawmakers got a sneak preview Wednesday of the court battle that likely awaits if they pass a law requiring genetically modified foods sold in Vermont to be labeled.

Industry representatives both for and against a labeling law gave heated testimony at the Statehouse to members of the Senate Judiciary Committee, where a bill that already passed the House now awaits action.

H.112 would mandate that most packaged foods be labeled if they contain genetically modified organisms. As currently written, dairy products, alcohol and meat, plus restaurant food, would be exempted from the law.

Sen. Dick Sears, D-Bennington, chair of Senate Judiciary, said he supports the bill, but his biggest concerns are the potential cost of litigation and the dairy exemption.

Assistant Attorney General Bridget Asay testified that the state may spend about $1 million defending the law in court. Even if it is successful, she said it would be hard to recover legal fees. If the state lost, the legal challenge could cost $5 million or more. The estimate includes the state's costs and potential reimbursement for a victorious plaintiff.

As senators finalize the bill for a committee vote by the end of March, two major amendments emerge as possibilities: One to require a legal defense fund to cover the costs of litigation, and another to eliminate the dairy exemption for fear it may undermine the bill's viability in court.