Gov. Janet Mills on Friday vetoed a bill that would allow farmworkers to unionize, saying it would subject farmers to “a complicated new set of laws that would require them to hire lawyers just to understand.”

Mills said the bill contains complicated provisions on mediation and arbitration between farmers and agricultural workers that would affect every farm in Maine with more than five workers, even if those employees are seasonal or part-time.

The measure, Mills said, “would further burden our small, family-owned farms by saddling them with increased costs” that would likely have to be passed along to consumers.

“While this bill is well intended, I fear its unintended consequence would discourage the growth of farms in Maine,” she said.

Mills’ veto was criticized by the Maine AFL-CIO, which said the measure would have allowed Maine farmworkers to push back against wage theft, sexual harassment and other abuses they face.

Farmworkers, the union said, are barred by law from forming unions and bargaining collectively, a prohibition that the AFL-CIO said is rooted in racism and excludes workers of color from labor protections.

“We are greatly dismayed that Gov. Mills vetoed legislation to grant farmworkers the fundamental human right to join together and form unions for fair treatment and a better life,” Matt Schlobohm, executive director of the Maine AFL-CIO, said in a statement. “This bill would have advanced racial justice and corrected a long-standing injustice.”

Mills said she is a “committed supporter of collective bargaining rights for workers generally,” but that Maine farms are primarily small, family-run operations and workers don’t need the same protections they would in areas where agriculture is dominated by factory farms owned by large corporate interests.

Maine farms that hire seasonal temporary workers already have to follow strict federal regulations, she said.

In her veto message, the governor said Maine farms face serious challenges that have been exacerbated by the COVID-19 pandemic and she doesn’t want to see farmers forced to deal with further hardships the law would create.